Measurements of the tensor analyzing ability of T20 in the reaction of fragmentation of deuterons into pions at zero angle and development of software for data acquisition systems of installations on polarized beams. Source of atomic hydrogen and deuterium with nuclear

Physicists have a habit of taking the simplest example of a phenomenon and calling it “physics,” and leaving more complex examples to the mercy of other sciences, say, applied mathematics, electrical engineering, chemistry or crystallography. Even solid state physics is only “semi-physics” for them, because it concerns too many special issues. For this reason, we will abandon many interesting things in our lectures. For example, one of the most important properties of crystals and most substances in general is that their electrical,
polarizability is different in different directions. If you apply an electric field in any direction, the atomic charges will move slightly and a dipole moment will arise; the magnitude of this moment depends very much on the direction of the applied field. And this, of course, is a complication. To make their life easier, physicists begin the conversation with the special case when the polarizability is the same in all directions. And we leave other cases to other sciences. Therefore, for our further considerations, we will not need at all what we are going to talk about in this chapter.

Tensor mathematics is especially useful for describing properties of substances that change with direction, although this is just one example of its use. Since most of you do not intend to become physicists, but intend to study real in a world where the dependence on direction is very strong, then sooner or later you will need to use a tensor. So, so that you don’t have a gap here, I’m going to tell you about tensors, although not in very detail. I want your understanding of physics to be as complete as possible. Electrodynamics, for example, we have a completely completed course; it is as complete as any course on electricity and magnetism, even an institute course. But our mechanics is not finished, because when we studied it, you were not yet so solid in mathematics and we could not discuss such sections as the principle of least action, Lagrangians, Hamiltonians, etc., which represent mostelegant way descriptions of mechanics. However, the complete set laws we still have mechanics, with the exception of the theory of relativity. To the same extent as electricity and magnetism, we have completed many sections. But we will never finish quantum mechanics; however, you need to leave something for the future! And yet, you should still know what a tensor is now.

In ch. 30 we emphasized that the properties of a crystalline substance are different in different directions - we say that it anisotropic. The change in the induced dipole moment with a change in the direction of the applied electric field is just one example, but it is the one we will take as an example of a tensor. We assume that for a given direction of the electric field, the induced dipole moment per unit volume P is proportional to the applied field strength E. (For many substances at not too large E this is a very good approximation.) Let the proportionality constant be α . Now we want to consider substances that have α depends on the direction of the applied field, for example the tourmaline crystal you know, which gives a double image when you look through it.

Suppose we discovered that for some selected crystal the electric field E 1 directed along the axis X, gives polarization P 1 directed along the same axis, and aloneequal in size to him electric field E 2 directed along the axis y, leads to some other polarization P 2, also directed along the axis u. What happens if an electric field is applied at an angle of 45°? Well, since it will simply be a superposition of two fields directed along the axes X And y, then the polarization P is equal to the sum of the vectors P 1 and P 2, as shown in Fig. 31.1, A. The polarization is no longer parallel to the direction of the electric field. It's not difficult to understand why this happens. There are charges in the crystal that are easy to move up and down, but which are very difficult to move to the sides. If the force is applied at an angle of 45°, then these charges move upward more readily than to the side. As a result of this asymmetry of internal elastic forces, the movement is not in the direction of the external force. Of course, the 45° angle is not highlighted. That induced polarization Not directed along the electric field, valid and in general. Before this, we were simply “lucky” to choose such axes X And y, for which the polarization P was directed along the field E. If the crystal were rotated with respect to the coordinate axes, then the electric field E 2 directed along the y axis would cause polarization both along the axis y, and along the axis X. In a similar way, the polarization P caused by a field directed along the axis X, would also have like X-, and y-components. So instead of fig. 31.1, A we would get something similar to Fig. 31.1, b. But despite all this complication, magnitude polarization P for any field E is still proportional to its magnitude.

Let us now consider the general case of arbitrary orientation of the crystal with respect to the coordinate axes. Electric field directed along the axis X, gives a polarization P with components on all three axes, so we can write

By this I only want to say that the electric field directed along the axis X, creates polarization not only in this direction, it leads to three components of polarization R x,RU And P z, each of which is proportional E x. We called the proportionality coefficients a xx, a yx and a zx(the first icon tells you which component we are talking about, and the second one refers to the direction of the electric field).

Similarly, for a field directed along the axis y, we can write

and for the field in the z-direction

Next we say that the polarization depends linearly on the field; so if we have an electric field E with components X And y, then the x-component of polarization P will be the sum of two R x, defined by equations (31.1) and (31.2), but what if E has components in all three directions x, y and z, then the polarization components P must be the sum of the corresponding terms in equations (31.1), (31.2) and (31.3). In other words, P is written in the form

The dielectric properties of a crystal are thus completely described by nine quantities (α xx, α xy,α xz, α yz , ...), which can be written as a symbol α ¡j. (Indices i And j replace one of three letters: x, y or z.) An arbitrary electric field E can be decomposed into components E x, E y And Ez. Knowing them, you can use the coefficients α ¡j and find P x, P y And P z , which together give the total polarization P. A set of nine coefficients α ¡j called tensor- in this example polarizability tensor. Just like three quantities (E x, E y,Ez) "form a vector E", and we say that nine quantities (α xx, α hu,...) “form a tensor α ¡j ».

Physicists have a habit of taking the simplest example of a phenomenon and calling it “physics,” and leaving more complex examples to the mercy of other sciences, say, applied mathematics, electrical engineering, chemistry or crystallography. Even solid state physics is only “semi-physics” for them, because it concerns too many special issues. For this reason, we will abandon many interesting things in our lectures. For example, one of the most important properties of crystals and most substances in general is that their electrical polarizability is different in different directions. If you apply an electric field in any direction, the atomic charges will shift slightly and create a dipole moment; the magnitude of this moment depends very much on the direction of the applied field. And this, of course, is a complication. To make their life easier, physicists begin the conversation with the special case when the polarizability is the same in all directions. And we leave other cases to other sciences. Therefore, for our further considerations, we will not need at all what we are going to talk about in this chapter.

Tensor mathematics is especially useful for describing properties of substances that change with direction, although this is just one example of its use. Since most of you are not going to become physicists, but intend to work in the real world, where the dependence on direction is very strong, sooner or later you will need to use a tensor. So, so that you don’t have a gap here, I’m going to tell you about tensors, although not in very detail. I want your understanding of physics to be as complete as possible. Electrodynamics, for example, we have a completely completed course; it is as complete as any course on electricity and magnetism, even an institute course. But our mechanics is not finished, because when we studied it, you were not yet so solid in mathematics and we could not discuss such sections as the principle of least action, Lagrangians, Hamiltonians, etc., which represent the most elegant way descriptions of mechanics. However, we still have a complete set of laws of mechanics, with the exception of the theory of relativity. To the same extent as electricity and magnetism, we have completed many sections. But we will never finish quantum mechanics; however, you need to leave something for the future! And yet, you should still know what a tensor is now.

In ch. 30 we emphasized that the properties of a crystalline substance are different in different directions - we say that it is anisotropic. The change in the induced dipole moment with a change in the direction of the applied electric field is just one example, but it is the one we will take as an example of a tensor. We assume that for a given direction of the electric field, the induced dipole moment per unit volume is proportional to the applied field strength. (For many substances, if not too large, this is a very good approximation.) Let the constant of proportionality be . Now we want to consider substances that depend on the direction of the applied field, for example the tourmaline crystal you know, which gives a double image when you look through it.

Suppose we discovered that for some selected crystal an electric field directed along the axis gives polarization directed along the same axis, and an electric field of the same magnitude directed along the axis leads to some other polarization also directed along axes What happens if an electric field is applied at an angle of 45°? Well, since it will simply be a superposition of two fields directed along the axes and , then the polarization is equal to the sum of the vectors and , as shown in Fig. 31.1, a. The polarization is no longer parallel to the direction of the electric field. It's not difficult to understand why this happens. There are charges in the crystal that are easy to move up and down, but which are very difficult to move to the sides. If the force is applied at an angle of 45°, then these charges move upward more readily than to the side. As a result of this asymmetry of internal elastic forces, the movement is not in the direction of the external force.

Fig. 31.1. Addition of polarization vectors in an anisotropic crystal.

Of course, the 45° angle is not highlighted. The fact that the induced polarization is not directed along the electric field is also true in the general case. Before this, we were simply “lucky” to choose such axes and for which the polarization was directed along the field. If the crystal were rotated with respect to the coordinate axes, then an electric field directed along the axis would cause polarization both along the axis and along the axis. Likewise, the polarization caused by a field directed along the axis would also have both - and - components. So instead of fig. 31.1, and we would get something similar to Fig. 31.1, b. But despite all this complexity, the amount of polarization for any field is still proportional to its magnitude.

Let us now consider the general case of arbitrary orientation of the crystal with respect to the coordinate axes. An electric field directed along the axis gives a polarization with components along all three axes, so we can write

By this I only want to say that an electric field directed along the axis creates polarization not only in this direction, it leads to three components of polarization, and, each of which is proportional to. We called the proportionality coefficients , and (the first icon indicates which component we are talking about, and the second refers to the direction of the electric field).

Similarly, for a field directed along the axis we can write

and for a field in the -direction

Next we say that the polarization depends linearly on the field; therefore, if we have an electric field with components and , then the -component of polarization will be the sum of two, defined by equations (31.1) and (31.2), but if it has components in all three directions, and , then the polarization components should be the sum of the corresponding terms in equations (31.1), (31.2) and (31.3). In other words, it is written in the form

UDC 539.18

DIFFERENTIAL SECTION AND VECTOR ANALYZING POWER OF THE ELASTIC DP SCATTERING REACTION AT 2 GeV ENERGY

A.A. Terekhin1),2)*, V.V. Glagolev2), V.P. Ladygin2), N.B. Ladygina2)

1) Belgorod State University, st. Studencheskaya, 14, Belgorod, 308007, Russia 2) Joint Institute for Nuclear Research, st. Joliot-Curie, b, Dubna, 141980, Russia, *e-mail: [email protected]

Annotation. The results of measurements and the procedure for processing data on the angular dependence of the vector analyzing power Ay and the cross section for the reaction of elastic dp scattering at an energy of 2 GeV are presented. The results obtained are in good agreement with international experimental data and with theoretical calculations performed within the framework of the relativistic multiple scattering model.

Key words: elastic dp scattering, differential cross section, analyzing ability.

Introduction

In connection with the active study of the nature of nuclear forces and non-nucleon degrees of freedom, interest in the simplest nuclear reactions and their polarization characteristics has recently increased greatly. The study of polarization effects is necessary to solve many modern problems in nuclear and particle physics. The structure of light nuclei has been intensively studied over the past few decades using both electromagnetic and hadronic probes. A significant amount of experimental data has been accumulated on the spin structure of light nuclei at small internucleon distances. The reactions p(d,p)d, 3He(d,p)4He or 3Iv(^, 3^)^ are the simplest processes with large momentum transfer. They can be used as a tool for studying the structure of the deuteron and 3^, as well as the mechanisms of interaction of nucleons at short distances.

The deuteron has a spin of 1, which provides ample opportunities to conduct numerous polarization experiments that provide new information about the behavior of various independent observables. In contrast to the static properties of the deuteron (binding energy, root-mean-square radius, magnetic moment), its structure at short distances has been studied much less well. High-momentum components in deuteron wave functions correspond to the region of small internucleon distances (g^m< 1 Фм), где нуклоны уже заметно перекрываются и теряют свою индивидуальность. Изучение поведения поляризационных наблюдаемых, чувствительных к спиновой структуре дейтрона на малых межнуклонных расстояниях, позволит

obtain information about the manifestation of non-nucleon degrees of freedom and relativistic effects.

In recent years, a number of studies have been carried out on polarization observables of the dp-elastic scattering response in various energy regions. The goal of the research is to study polarization observables at intermediate and high energies. For 270 MeV, data were obtained on the reaction cross section, polarization transfer coefficients from the deuteron to the proton Kt, deuteron vector Ау and tensor А^ analyzing abilities, as well as polarization Рy. The cross section and vector analyzing power are well described by Faddeev calculations based on new MM potentials, using the Taxon-Melbourne three-nucleon force. On the other hand, the tensor analyzing ability Ау, transmission coefficients K^ and polarization Рy are not described by these calculations. Also for 270 MeV, data were obtained on the cross section, Ay and A^ for the angular range in cm. Comparison with Faddeev’s calculations shows good agreement of all components of the analyzing abilities. A noticeable discrepancy is observed in the section (30%) near the angle β* = 120°.

Rice. 1. Distribution of events by scattering angle in*

With increasing energy, relativistic effects and non-nucleon degrees of freedom begin to play an increasingly important role. Another important aspect is that the analysis capabilities of the reaction are sufficiently important to perform effective polarimetry over a wide range of deuteron energies. Recently, data were obtained on the analyzing abilities of Ay and A^ at 880 MeV in the angular range of 60°< в* < 140° .

1. Experiment

Data acquisition was carried out in a series of experiments in a 100 cm hydrogen chamber exposed to an extracted deuteron beam from a synchrophasotron with an energy of 2 GeV. The use of bubble chambers is noteworthy in that observation can be carried out under 4p geometry conditions. A characteristic feature of the hydrogen chamber is that

that interaction occurs only with protons (the so-called pure target). In addition, the camera is located in a magnetic field, which helps to identify the mass of secondary particles.

Rice. 2. Distributions over the azimuthal angle p for different angles

The Polaris source of polarized deuterons provided deuterons with theoretical values ​​of vector and tensor polarizations: (Pz, Pzz) = (+2/3, 0), (-2/3, 0) - polarized modes and (0, 0) - unpolarized fashion. These states alternated in accelerator cycles, and the corresponding marks were transmitted to the camera’s recording equipment. Events were selected on viewing tables and measured on semi-automatic machines and the HPD machine at JINR. Mathematical processing was carried out using adapted CERN programs THRESH (geometric reconstruction) and GRIND (kinematic identification), as well as a chain of auxiliary programs for selecting reactions and recording the results on the DST (total results tape). Events were classified according to the results of the kinematic identification program (GRIND) using ionization loss assessment data. The service information necessary for subsequent processing was imprinted into each frame of the film using an information board. In particular, when working in a beam of polarized deuterons, information about the state of polarization that came in each acceleration cycle from the source of polarized particles "POLARIS" was imprinted in encoded form. In our case - vector. This information was stored for each event and on the DST.

Deuteron polarization was calculated from an analysis of the azimuthal asymmetry of recoil nucleons during quasi-free scattering on a proton target. The analysis was carried out both for all events and for events in the region of small transmitted impulses.

owls (to< 0.065 ОеУ/с), т.к. в последней дейтронная и нуклонная векторные поляризации приблизительно равны. Полученное значение дейтронной поляризации равнялось Р? = 0.488 ± 0.061 .

2. Data processing

The values ​​for the vector analyzing ability Ау were found by processing events corresponding to different polarization states of the deuteron beam (polarization modes 1 and 2 correspond to such states). The distribution of scattering angle b* in the center of mass system is shown in Fig. 1.

Rice. 3. Distribution of the value of R over the azimuthal angle p for scattering angle values ​​of 12°< в < 14°

The working part of the spectrum was divided into successive intervals (bins). The number of events in each interval was normalized to the width of the last one. For each interval, a distribution based on the azimuthal angle of the river was constructed. For small scattering angles b*, event losses are significant (Fig. 2), due to the fact that at the viewing stage, tracks of recoil protons with momenta less than 80 MeV/c are no longer visible in the chamber. In addition, there are azimuthal losses associated with the camera optics. In this region, intervals corresponding to lost events were excluded. Elimination by intervals was carried out symmetrically with respect to the values ​​p = 0° and p = 180°. The remaining events were used to calculate the differential cross section and analysis power.

For each selected interval along the angle, the value R was calculated:

where N1 and N2 are the numbers of events for spin mode values ​​1 and 2, respectively. The obtained data were approximated by the function vidar0+p1 v(p). In Fig. 3, as

As an example, the distribution over the azimuthal angle is given for angles of 12°< в* < 14° в с.ц.м.

For each interval of the distribution over β*, the values ​​of the parameters p0 and p1 of the approximating function p0 + p1 w(p) were obtained. The parameter p0 has the meaning of the so-called false asymmetry. The estimated value of false asymmetry, obtained by approximating the values ​​of the parameter p0, does not exceed 5% and is p0 = -0.025± 0.014. The parameter p1 is related to the analyzing ability of the expression:

Rice. 4. Analyzing ability Ay of the dp-elastic scattering reaction at an energy of 2 GeV.

Solid symbols are the results of this experiment, open symbols are data obtained at ANL. Line - results of calculations within the framework of the multiple scattering model

The obtained values ​​for the vector analyzing ability y are presented in Fig. 4. They agree with sufficient accuracy with the data obtained at ANL and with theoretical calculations.

To calculate the reaction cross section for dp-elastic scattering, events obtained from both polarized and unpolarized deuteron beams were used. An analysis was carried out of the cosine distribution of the scattering angle b* in the center of mass system. For each interval Дв* the corresponding interval A cos в* was taken (Fig. 5,6). Then normalization was carried out to the width of the interval A cos in*. The reaction cross section was calculated using the formula:

where the vector polarization of the beam is py = 0.488 ± 0.061.

where A = 0.0003342 ± 0.0000007 [mb/event] is the millibarn equivalent of the event, A cos b* is the width of the interval in the distribution of the number of events by the cosine of the scattering angle b*.

Rice. B. Distribution of events by scattering angle O*

Rice. b. Distribution of events by cos O*

As the scattering angle b* increases, the deviation from isotropy decreases. At β* > 20° the distribution becomes isotropic. In the distribution by azimuthal angle p, bins corresponding to lost events were excluded. The exclusion was carried out within the same limits as when calculating the analyzing ability of Ay.

Rice. 7. Differential sections in cm. Solid symbols - the results of this experiment, open symbols - data from the work, solid line - results

theoretical calculations

The obtained values ​​of the reaction cross section depending on the angle b* were compared with

world data, as well as with theoretical calculations performed within the framework of the relativistic model of multiple scattering and, as can be seen from Fig. 7 are in good agreement.

Conclusion

Values ​​were obtained for the vector analyzing ability and the cross section for the reaction of elastic dp scattering at an energy of 2 GeV in an angular range of 10°< в* < 34° в с.ц.м. Проведено сравнение с мировыми данными и с теоретическими расчетами, выполненными в рамках релятивистской модели многократного рассеяния. Выявлено хорошее согласие теоретических и экспериментальных значений.

Literature

1. Day D. et al. // Phys.Rev.Lett. - 1979. - 43. - P.1143.

2. Lehar F. // RNP: from Hundreds of MeV to TeV. 2001. V. 1. P. 36.

3. Sakai H. et al. Precise measurement of dp elastic scattering at 270 MeV and three-nucleon force effects // Phys Rev Lett. - 2000. - 162. - P.143.

4. Coon S.A. et.al. // Nucl.Phys. - 1979. - A317. - P.242.

5. Sakamoto N. et al. Measurement of the vector and tensor analyzing powers for the dp elastic scattering at Ed = 270 MeV // Phys. Lett. - 1996. - B.367. - P.60-64.

6. Kurilkin P.K. et al. Measurement of the vector and tensor analyzing powers in dp elastic scattering at the energy of 880 MeV // European Physical Journal. Special Topics. - 2008. -162. - P.137-141.

7. Anishchenko, et al. AIP Conf. Proc. - 95 (1983). - P.445.

8. CERN T.C.Program Library, sec. THRESH, 1.3. - 1966.

9. CERN T.C.Program Library, sec. GRIND, 30.10. - 1968.

10. Glagolev V.V. et al. The deuteron D-state probability // Zeitchrift fur Physik. - 1996. - A 356. - P.183-186.

11. Glagolev V.V. Optics of a meter-long hydrogen bubble chamber // JINR preprint.

12. Haji Saica M. // Phys. Rev. - 1987. - C36. - P.2010.

13. Ladygina N.B. Measurement of the vector and tensor analyzing powers in dp elastic scattering at the energy of 880 MeV // European Physical Journal. Special Topics. - 2008. - 162. -P.137-141.

14. Bugg D.V. et al. Nucleon-Nucleon Total Cross Sections from 1.1 to 8 GeV/c // Phys. Rev. Lett. - 1996. - 146. - P.980-992.

15. Bennett G. W. et al. Proton-deuteron scattering at 1 BeV // Phys. Rev. Lett. - 1976. - 19. -P.387-390.

DIFFERENTIAL CROSS SECTION AND VECTOR ANALYZING POWER IN D-P ELASTIC SCATTERING AT 2.0 GeV A.A. Terekhin 1)’2)*, V.V. Glagolev2), V.P. Ladygin2), N.B. Ladygina2)

Belgorod State University,

Studencheskaja St., 14, Belgorod, 308007, Russia

2) Joint Institute for Nuclear Researches,

Zholio-Kjuri St., 6, Dubna, 141980, Russia, * e-mail: [email protected]

Abstract. The results of measurements as well as handling procedure for the data on the angular dependence of the vector analyzing powers Ay and differential cross section for dp-elastic scattering at Ed = 2 GeV are reported. The obtained data are in good agreement with the existing data and theoretical calculations made in the framework of the relativistic multiple scattering model.

Key words: elastic dp-scattering, differential cross-section, analysis possibility.

480 rub. | 150 UAH | $7.5 ", MOUSEOFF, FGCOLOR, "#FFFFCC",BGCOLOR, "#393939");" onMouseOut="return nd();"> Dissertation - 480 RUR, delivery 10 minutes, around the clock, seven days a week and holidays

Isupov Alexander Yurievich. Measurements of the tensor analyzing ability T20 in the reaction of fragmentation of deuterons into pions at zero angle and development of software for data acquisition systems of installations on polarized beams: dissertation... candidate of physical and mathematical sciences: 01.04.16, 01.04.01.- Dubna, 2005. - 142 p.: ill. RSL OD, 61 06-1/101

Introduction

I Experiment setup 18

1.1 Motivation 18

1.2 Experimental setup 20

1.3 Methodological measurements and modeling 24

1.4 Organization and principle of operation of the trigger 33

II Software 40

II.1 Introductory remarks 40

II.2 Data acquisition and processing system qdpb 42

II.3 Configurable views of data and hardware 56

II.4 Session-dependent data presentation tools. 70

II.5 DAQ system SPHERE 74

II. 6 Polarimeter data acquisition systems 92

III. Experimental results and their discussion 116

III.1 Analysis of sources of systematic errors 116

III.2 Experimental data 120

Sh.3. Discussion of experimental data 127

Conclusion 132

Literature 134

Introduction to the work

B.1 Introduction

The dissertation paper presents experimental results of measurements of the tensor analyzing ability of Ggo in the reaction of fragmentation of tensorly polarized deuterons into cumulative (sub-threshold) pions. The measurements were carried out by the SPHERE collaboration on a beam of tensorly polarized deuterons at the accelerator complex of the High Energy Laboratory of the Joint Institute for Nuclear Research (LHE JINR, Dubna, Russia). The study of polarization observables provides more detailed, in comparison with reactions with unpolarized particles, information about the Hamiltonian of interaction, reaction mechanisms and the structure of particles participating in the reaction. To date, the question of the properties of nuclei at distances smaller than or comparable to the size of a nucleon has been insufficiently studied, both from experimental and theoretical points of view. Of all the nuclei, the deuteron is of particular interest: firstly, it is the most studied nucleus from both experimental and theoretical points of view. Secondly, for the deuteron, as the simplest nucleus, it is easier to understand the reaction mechanisms. Third, the deuteron has a nontrivial spin structure (spin equal to 1 and nonzero quadrupole moment), which provides broad experimental opportunities for studying spin observables. The measurement program, within the framework of which the experimental data presented in the dissertation work was obtained, is a natural continuation of studies of the structure of atomic nuclei in reactions with the production of cumulative particles in the collision of unpolarized nuclei, as well as polarization observables in the deuteron breakup reaction. The experimental data presented in the dissertation work make it possible to advance the understanding of the spin structure of the deuteron at small internucleon distances and complement the information on the structure of the deuteron obtained in experiments with a lepton probe and in studying the breakup reaction of tensorly polarized deuterons, and therefore seem relevant. To date, the data presented in the dissertation work are the only ones, since to carry out this kind of research beams of polarized deuterons with an energy of several GeV are needed, which are currently and in the next few

years will be available only at the LHE JINR accelerator complex, where it is natural to continue research in this direction. The data mentioned were obtained as part of an international collaboration, presented at a number of international conferences, and also published in peer-reviewed journals.

Further in this chapter we will provide information about cumulative particles necessary for further presentation, definitions used in describing polarization observables, and also give a brief overview of the results known in the literature on the deuteron breakup reaction.

B.2 Cumulative particles

Research into the laws governing the birth of cumulative particles has been conducted since the early seventies of the 20th century. The study of reactions with the production of cumulative particles is interesting because it provides information on the behavior of the high-momentum (> 0.2 GeV/c) component in fragmenting nuclei. The indicated large internal momenta correspond to small ones (xx > 1, where the cross sections become very small.

First of all, let us define what will be further understood by the term “cumulative particle” (see, for example, the references therein). Particle With, born in reaction:

Ar + AP -Ї- c + X, (1)

is called "cumulative" if the following two conditions are met:

particle c is born in a kinematic region inaccessible during collisions of free nucleons having the same momentum per nucleon as the A/ and nuclei AC in reaction (1);

particle With belongs to the fragmentation region of one of the colliding particles, i.e. must be done either

\YAt-Yc\^\YAn-Yc\., (2)

Where Yi is the speed of the corresponding particle z. From the first condition it follows that at least one of the colliding particles must be a nucleus. From the second condition it is clear that colliding particles are included in this definition asymmetrically. In this case, the particle that is closer in speed to the cumulative one will be called fragmenting, and the other of the colliding particles will be called the particle on which fragmentation occurs. Typically, experiments with the birth of cumulative particles are carried out in such a way that the detected particle lies outside the rapidity interval [Ul„, )%]. The cumulative particle is detected either in the rear (fragments the target) or in the front (fragments the beam) hemisphere with a sufficiently large momentum. In this case, the second condition reduces to the requirement of a sufficiently large collision energy:

\UUp - UWith\ « \YAl~Yc\ = |U L// - Yc\ + \YAn-YAl\ . (4)

It follows from experimental data (see, for example, , , , , , , , , ) that for experiments on a fixed target, the shape of the spectrum of cumulative particles weakly depends on the collision energy, starting with the energies of the incident particles Th> 3-g-4 GeV. This statement is illustrated in Fig. 1, reproduced from the work, which shows the dependences on the energy of the incident proton: (b) the ratio of the yields of pions of different signs 7r~/tr + and (a) the inverse slope parameter of the spectrum T 0 for approximation Edcr/dp = Sehr(- T^/Tq) cross sections for the production of cumulative pions measured at an angle of 180. This means that the independence of the shape of the spectra from the primary energy begins with the difference in the velocities of the colliding particles \Yau- YAl\ > 2.

Another established pattern is the independence of the spectra of cumulative particles from the type of particle on which fragmentation occurs (see Fig. 2).

Since the dissertation examines experimental data on the fragmentation of polarized deuterons into cumulative pions, the patterns established in reactions with the production of cumulative particles (dependence on the atomic mass of the fragmenting nucleus, dependence on the type of detected particle, etc.) will not be discussed in more detail. If necessary, they can be found in the reviews: , , , .

- h

h 40 ZO

M і-

Present experiment

O 7G*1TG"І

+ -

Present experiment v Reference 6

Rice. 1: Dependence on the energy of the incident proton (TR) (a) inverse slope parameter T 0 and (b) output ratio tt~/tg + , integrated starting from a pion energy of 100 MeV. The figure and data marked with circles are taken from . Data marked with triangles are cited in from .

B.3 Description of polarized states of particles with spin 1

For the convenience of further presentation, we provide a brief overview of the concepts , , which are used to describe the reactions of particles with spin 1.

Under ordinary experimental conditions, an ensemble of particles with spin (beam or target) is described by the density matrix R, the main properties of which are the following:

Normalization Sp(jo) = 1.

Hermitianity p = p + .

D-H"

.,- WITHf

ABOUT - Si 4 -Pbw l

, . f,

" -" -. і.. -|-і-

Cumulative scale variable XWith

Rice. 2: Dependence of the cross section for the production of cumulative particles on the cumulative scale variable XWith (57) (see paragraph III.2) for fragmentation of a deuteron beam on various targets into pions at zero angle. The drawing is taken from the work.

3. Average from the operator O is calculated How (O) = Sp(Op).

The polarization of an ensemble (to be specific, a beam) of particles with spin 1/2 is characterized by the direction and average value of the spin. As for particles with spin 1, one should distinguish between vector and tensor polarizations. The term "tensor polarization" means that the description of particles with spin 1 uses a tensor of the second rank. In general, particles with spin / are described by the rank tensor 21, so for / > 1 one should distinguish between polarization parameters of the 2nd, 3rd ranks, etc.

In 1970, at the 3rd International Symposium on Polarization Phenomena, the so-called Madison Convention was adopted, which, in particular, regulates the designations and terminology for polarization experiments. When recording a nuclear reaction L(a, b)V Arrows are placed above particles that react in a polarized state or whose polarized state is observed. For example, the notation 3 H(rf,n) 4 He means that an unpolarized 3 H target is bombarded by polarized deuterons d and that polarization of the resulting neutrons is observed.

When talking about measuring the polarization of a particle b in a nuclear reaction, we mean the process A(a, b)B, those. in this case, the beam and the target are not polarized. The parameters that describe changes in the reaction cross section when either the beam or the target (but not both) are polarized are called the analyzing abilities of the reaction of the form A(a, b)B. Thus, except in special cases, polarizations and analyzing abilities should be clearly distinguished, since they characterize different reactions.

Type reactions A(a, b)B, A(a, b)B etc. are called polarization transfer reactions. Parameters relating the spin moments of a particle b and particles a, are called polarization transfer coefficients.

The term "spin correlations" is applied to experiments studying reactions of the form A(a, b)B And A(a, b)B, and in the latter case the polarization of both resulting particles must be measured in the same event.

In experiments with a beam of polarized particles (measurements of analyzing abilities) in accordance with the Madisonian Convention, the axis z guided by the momentum of the beam particle kjn, axis y - By To(P X kout(i.e. perpendicular to the reaction plane), and the axis X must be directed so that the resulting coordinate system is right-handed.

Polarization state of a system of particles with spin I can be completely described by (2/+1) 2 -1 parameters. Thus, for particles with spin 1/2 there are three parameters pi form a vector R, called the polarization vector. An expression in terms of the spin 1/2 operator, denoted A, following:

Pi =yy,Z, (5)

where the angle brackets mean averaging over all particles of the ensemble (in our case, the beam). Absolute value R limited \р\ 1. If we incoherently mix n+ particles in a pure spin state, i.e. completely polarized in some given direction, and n_ particles completely polarized in the opposite direction, the polarization will be p =" + ^~ , or

+ p = N + ~N_, (6)

if under N + = PP+ P _ and JV_ = ~jf^- understand the fraction of particles in each of the two states.

Since the polarization of particles with spin 1 is described by a tensor, its representation becomes more complicated and less clear. Polarization parameters are some observable quantities

spin operator 1, S. Two different sets of definitions are used for the corresponding polarization parameters - Cartesian tensor moments ri rts and spin tensors tjsq. In Cartesian coordinates, according to the Madisonian Convention, the polarization parameters are defined as

Pi= (Si)(vector polarization), (7)

pij- -?(SiSj.+ SjSi)- 25ij(tensor polarization), (8)

Where S- spin 1 operator, i, j= x,y,z. Because the

S(S+1).= 2 , (9)

we have a connection

Рхх + Руу + Pzz = 0 (10)

Thus, tensor polarization is described by five independent quantities (pzx, Ruh, Rxy, pXz, Pyz)-> which, together with the three components of the polarization vector, gives eight parameters to describe the polarized state of a particle with spin 1. The corresponding density matrix can be written as:

P = \i^ + \is + \vij(SiSj+ SjSi)).. (11)

Description of the polarization state in terms of spin tensors is convenient, since they are simpler than Cartesian tensors and are transformed upon rotation of the coordinate system. The spin tensors are related to each other by the following relation (see):

hq~ N(fc i9i fc 2&|fcg)4 w ,4 2(ft , (12)

Where (kiqik 2 q2\kq) ~ Clebsch-Gordan coefficients, and N- normalization coefficient chosen so that the condition is satisfied

Sp.(MU) = (^ + 1)^,^ (13)

The lowest spin moments are:

І 11 = 7^ (^ + ^y) " (14)

t\ -\ = -^(Sx-iSy) .

For spin/index To runs values ​​from 0 to 21, a |d| j. Negative values q can be discarded because there is a connection tk _ q = (-1)41 + $№ spin 1 spherical tensor moments are defined as

t\\ ~ ~*-(Sx ) (vector polarization),

tii.= -&((Ss+iSy)Sg.+ Sx(Sx+iSy)) ,

hi = 2 ((Sx+iSy) 2 ) (tensor polarization).

Thus, vector polarization is described by three parameters: real t\o and comprehensive "tu, and tensor polarization - five: real I20 and complex I2b ^22-

Next, we consider the situation when the spin system has axial symmetry relative to the C axis (designation z leave for the coordinate system associated with the reaction under consideration, as described above). This particular case is interesting because beams from sources of polarized ions usually have axial symmetry. Let us imagine such a state as an incoherent mixture containing a fraction N+ particles with spins along, fraction N- particles with spins along - and the fraction JVo of particles with spins uniformly distributed along directions in a plane perpendicular to. In this case, only two polarization moments of the beam are nonzero, t to (or sch) And t 2 Q(or R#). Let us direct the quantization axis along the symmetry axis C and replace i in the notation with t and z by (". It is obvious that (*%) is simply equal to N + - iV_, and in accordance with (15) and (7):

ty = \-(iV+-JV_) or (17)

p = (N + - i\L) (vector polarization).

From (16) and (8) it follows that

T2o = -^(l-3iVo) or (18)

Ptf= (1 - 3iVo) (tensor polarization or alignment),

where it is used that (JV+ + i\L) = (1 - iV 0).

If all 2nd rank moments are missing (N 0 = 1/3), they speak of purely vector polarization of the beam. The maximum possible polarization values ​​of such a beam

tii" = yfifi or C 19)

pmax. _ 2/3 (pure vector polarization).

For the case of purely tensor polarization (tu = 0) from equations (17) and (18) we obtain

-у/2 2 oil (20)

The lower limit corresponds to No= 1, top - N+ ~ N_ = 1/2.

In general, the axis of symmetry WITH, polarized beam from the source can be oriented in any way with respect to the coordinate system xyz associated with the reaction in question. Let us express the spin moments in this system. If the axis orientation ( specified by angles /3 (between axes z and C) and f(rotation on - f around the axis z brings the C axis into plane yz), as shown in Fig. 3, and in the system WITH, beam polarizations are equal T\ 0 , t 20, then the tensor moments in the system xyz are equal:

Vector moments: Tensor moments:

t 20 = y(3cos 2 /?- i) , (21)

itn = ^8 IP0ЄIf. til= " %T2 % Silljgcos/fe**",

y/2 y/2

In the general case, the invariant section a = Edajdp reactions A(a,b)B is written as:

Quantities T)sch are called analyzing reaction abilities. The Madisonian Convention recommends denoting tensor analysis abilities as Tkq (spherical) and AitAC(Cartesian). Four analyzing abilities - vector GTAnd and tensor T 20, TG\ And Tii

Rice. 3: Orientation of the axis of symmetry ( polarized beam relative to the coordinate system xyz associated with the reaction xz- reaction plane, /3 - angle between axes z(direction of the incident beam) and, rotation by - f around the axis z drives the axis; into the plane yz.

- are valid due to parity conservation, and 7\ 0 = 0. Taking into account these restrictions, equation (22) takes the form:

a = cro, , , . In general, the obtained experimental spectra are well described by the spectra

tator mechanism using generally accepted VFDs, for example the Reid or Paris VFDs.

Rice. 5: Distribution of nucleons by relative momenta in the deuteron, extracted from experimental data for various reactions involving the deuteron. The drawing is taken from the work.

So, from Fig. 5 it can be seen that the momentum distributions of nucleons in the deuteron, extracted from the data for the reactions: inelastic electron scattering on the deuteron, are in good agreement d(e,e")X, elastic proton-deuteron scattering back p(d,p)d, and the collapse of the deuteron. Except for the internal pulse interval To From 300 to 500 MeV/c the data is described by the spectator mechanism using the Paris VPD. Additional mechanisms have been invoked to explain the discrepancies in this area. In particular, taking into account the contribution from pion rescattering in the intermediate state , , allows us to satisfactorily describe the data. However, the uncertainty in the calculations is about 50 % due to uncertainty in knowledge of the vertex function irN, which, in addition, in such calculations must be known outside the mass surface. In order to explain the experimental spectra, the work took into account the fact that for large internal momenta (i.e., small internucleon distances)

yaniy Inn- 0,2/"To) non-nucleon degrees of freedom may appear. In particular, in this work an admixture of a six-quark component was introduced \6q), the probability of which was ~-4.%.

Thus, it can be noted that, in general, the spectra of protons obtained from the fragmentation of deuterons into protons at zero angle can be described up to internal momenta of ~ 900 MeV/c. In this case, it is necessary either to take into account the diagrams following the impulse approximation, or to modify the VFD taking into account the possible manifestation of non-nucleon degrees of freedom.

Polarization observables for the deuteron breakup reaction are sensitive to the relative contributions of VPD components corresponding to different angular momenta, so experiments with polarized deuterons provide additional information about the deuteron structure and reaction mechanisms. Currently, there is extensive experimental data on tensor analyzing ability T 2 O for the reaction of breakup of tensorly polarized deuterons. The corresponding expression in the spectator mechanism is given above, see (30). Experimental data for T 2 q, obtained in works , , , , , , , , , are shown in Fig. 6, from which it is clear that already starting from internal momenta of the order of 0.2 H - 0.25 GeV/c, the data are not described by generally accepted two-component VFDs.

Taking into account the final state interaction improves the agreement with experimental data up to momenta of the order of 0.3 GeV/c. Taking into account the contribution of the six-quark component in the deuteron makes it possible to describe data up to internal momenta of the order of 0.7 GeV/c. Behavior T 2 O for pulses of the order of 0.9 - b 1 GeV/c is in best agreement with calculations within the framework of QCD using the method of reduced nuclear amplitudes, , taking into account the antisymmetrization of quarks from different nucleons.

Thus, to summarize the above:

Experimental data for the cross section for fragmentation of unpolarized deuterons into protons at zero angle can be described within the framework of the nucleon model.

Data for T20 have so far been described only using non-nucleon degrees of freedom.

Methodical measurements and modeling

Measurements of the tensor analyzing ability G20 of the reaction d + A - (0 - 0) + X fragmentation of relativistic polarized deuterons into cumulative pions were carried out on channel 4B of the slow extraction system of the Synchrophasotron LHE JINR. Channel 4B is located in the main measuring hall of the accelerator complex (the so-called building 205). Polarized deuterons were created by the POLIA-RIS source, which is described in.

The measurements were carried out under the following conditions: 1. the stretching value (extraction time) of the beam was 400–500 ms; 2. repetition rate 0.1 Hz; 3. the intensity varied in the range from 1,109 to 5,109 deuterons per discharge; 4. the tensor polarization value of the deuteron beam was pzz 0.60-0.77, changing slightly (by no more than 10%, see) within a given series of measurements, and the vector polarization admixture was pz « 0.20 -=- 0 .25; 5: the quantization axis for polarization was always directed vertically; 6. Three states of polarization were provided - “+” (positive sign of polarization), “-” (negative sign of polarization), “0” (no polarization), changing each accelerator cycle, so that in three successive cycles the beam had different states of polarization. In the first series of measurements, carried out in March 1995, the magnitude of vector and tensor polarization was measured at the beginning and end of a full cycle (session) of measurements using a high-energy polarimeter described in the work - the so-called. ALPHA polarimeter.

In the first series of measurements, , , , was used shown in Fig. 8 configuration of the setup with a target located at focus F3 (we will call it “first setup” for brevity).

The extracted beam of primary deuterons was focused by a doublet of quadrupole lenses onto a target located at focus F3. The intensity distribution on the target in a plane perpendicular to the direction of the beam was close to a Gaussian distribution with dispersions mxa 6 mm and oy ≈ 9 mm along the horizontal and vertical axes, respectively. Carbon targets (50.4 g/cm2 and 23.5 g/cm2) of cylindrical shape with a diameter of 10 cm were used, which made it possible to assume that the entire primary beam hits the target.

The intensity of the deuteron beam incident on the target was monitored using an ionization chamber 1C (see Fig. 8), located in front of the target at a distance of 1 m from it, and two scintillation telescopes Mi and M2, each with three counters, aimed at aluminum foil 1 mm thick. Absolute calibration of the monitors was not carried out. The difference in determining the relative intensity from different monitors reached 5%. This difference was included in the systematic error.

Scintillation counters at foci F4 (F4b F42), F5 (F5i) and F6 (F6i) were used to measure time of flight at 74 meter (F4-F6) and 42 meter (F5-F6) bases. Scintillation counters Si and Sz, and, if necessary, a Cherenkov counter C (with a refractive index n = 1.033) were used to generate a trigger. Scintillation hodoscopes HOХ, HOY, HOU, H0V were used to monitor the beam profile in F6. The characteristics of the counters are given in Table 1. The first setup of the experiment, due to the presence of six deflecting magnets, made it possible to have a negligible (less than 10-4) background/signal ratio for time-of-flight spectra even on positively charged particles. Suppression of protons (by two orders of magnitude) in the trigger using a Cherenkov counter was used to reduce the dead time. The inconvenience of such a setup is due to the need to reconfigure a large number of magnetic elements. Therefore, experimental data in the first setting were collected with a pion momentum fixed by the 4V channel (3.0 GeV/c), the degree of subthreshold of which was increased by decreasing the deuteron momentum. In the second series of measurements, carried out in June-July 1997, data were collected in a slightly different setup configuration with a target located at the F5 focus (hereinafter referred to as the “second setup”), as shown in Fig. 9. In this setting, the load on the head counters increases, especially when measuring on positive particles. To reduce the influence of such loads, an NT scintillation hodoscope was used in the head part, which consisted of eight plastic scintillators viewed from both sides of the FEU-87. Sigaals from this hodoscope were used for time-of-flight analysis (based on 30 m), which in this case was carried out for each element independently. The position and profile of the beam (ax 4 mm, ty = 9 mm) on the target were monitored with a wire camera, the intensity - with an ionization chamber 1C and scintillation telescopes M and Mg. Measurements of the second series were carried out with a hydrogen target (7 g/cm2), a beryllium target (36 g/cm2) in the shape of a parallelepiped with a minimum transverse (relative to the beam) size of 8x8 cm2 and a carbon target (55 g/cm2) of a cylindrical shape with a diameter of 10 cm. The dimensions of the counters for the second experimental setup are given in Table 2. Rotation angles for all deflection magnets are shown in Table 3.

Configurable data and hardware views

Recommended way to write a worker module: reads and writes are performed as buffered input and output operations on the standard input and output streams of a blocking process; the SIGPIPE signal and the EOF state lead to the normal termination of the process. The working module can be implemented both dependent and independent of the composition of the collected data (i.e., the contents of packet bodies) and the equipment being serviced (hereinafter referred to as “session-dependent” and “session-independent”4, respectively).

The control module is a process that does not work with a stream of data packets and is intended, as a rule, to control some element(s) of the qdpb system. The implementation of such a module, therefore, does not depend either on the contents of the packet stream or on the contents of the packet bodies, which ensures its universality (session independence).

In addition, processes that receive source data not through packet streams are also classified here, for example, modules for presenting (visualizing) processed data in the current implementation of the DAQ SPHERE system, see paragraph II.5. Such a control module can be implemented in either a session-independent or session-dependent manner.

A service module is a process that is designed to organize packet streams and does not make changes to them. It can read from and/or write to a packet stream, and the contents of the service module's input and output streams are identical. The implementation of the service module does not depend on the contents of the packet stream or the contents of the packet bodies, which ensures its universality.

A branch point is the starting and/or ending point for multiple packet streams and is designed to create multiple identical output packet streams from several different input packet streams (produced by different sources). The branch point does not change the contents of the packets. The branch point implementation is independent of the contents of packet streams, making it universal. The order of packets from different input streams in the output stream is random, but the order of packets from each input stream is preserved: The branch point also implements a packet buffer and provides controls for it. It is recommended to implement the branch point as part of the OS kernel (in the form of a loadable module or driver), providing the corresponding system call(s) to manage its own state, output this state externally, manage the packet buffer, and register the input and output streams working with it. Depending on the internal state, a branch point system call receives (blocks receiving, receives and ignores) packets from any input stream and sends (blocks sending) all received packet(s) to output streams by system call.

The event stitcher5 is a variant of the branch point, also designed to create several identical output packets from several different (from different sources) input streams. The event stitcher modifies the contents of the packets as follows: the header of each of the output packets is obtained by making a new packet header, and the body is obtained by sequentially connecting the bodies of one or more (one from each registered input stream - the so-called input channel) so-called. "corresponding" 6 input packets to it. In the current implementation, matching input and output packets requires: - a match of types (header.type) of input and output packets declared for each input channel when registering it, and - a match of numbers (header.num) of input packets for match candidates in all input channels. The term “event stitcher” was introduced because it more accurately characterizes the proposed (fairly simple) functionality, in contrast to rather complex systems called “event builder”. Packets with types that do not have declared matches are discarded when entering input channels. Packets with numbers that do not find matches in all input channels are discarded. The implementation of the event stitcher is independent of the contents of the packets. It is recommended to implement the event stitcher as part of the OS kernel (in the form of a loadable module or driver), which provides the appropriate system call(s) to manage its own state, output this state externally, and register the input and output streams working with it. The supervisor is a control (or worker, if control packages are implemented) module that carries out at least starting, stopping and control actions in the qdpb system according to commands from the system user (hereinafter referred to as the “operator”). The correspondence of the supervisor's actions to the operator's commands is described in the configuration file of the first sv.conf(S). In the current implementation, the configuration file is a makefile. The elements of the qdpb system are controlled through the mechanisms provided by these elements. The managed elements of the qdpb system are: elements of the OS kernel (loadable modules of the hardware maintenance subsystem, branch point(s), event stitcher(s); working modules. Control of other elements of the qdpb system is not provided, as well as reaction to situations in the system. For remote control, i.e. control elements of the qdpb system on computers other than the supervisor executing the process (hereinafter referred to as “remote computers”), the supervisor launches control modules on them using standard OS tools - rsh(l) / ssh(l), rcmd(3) win rpc(3 ). For a dialogue between an operator and a supervisor, the latter can implement an interactive graphical user interface (Graphics User Interface, hereinafter referred to as “GUI”) or an interactive command line interface. Some elements of the qdpb system, which have their own GUI, can be controlled by the operator directly, without the participation of a supervisor (for example, data presentation modules). The above project was largely implemented. Let's take a closer look at the key implementation points.

Polarimeter data acquisition systems

By default, the sphereconf utility configures the specified loadable module module to work with the CAMAC hardware "kkO" driver. No specific information is transferred to the loaded module. When you specify a command line option, sphereconf tests the configuration of the specified loadable module and prints it to the error output stream. The default behavior of the sphereconf utility is modified by the command line switches above. The sphereconf utility returns zero if successful and positive otherwise. The sphereoper(8) control utility for the CAMAC interrupt handler is called sphereoper and has the following command interface: sphereoper [-v] [-b # ] startstop)statusinitfinishqueclJcntcl By default, sphereoper executes the oper() system call with the subfunction fun specified by the first positional argument of the command lines in the loadable module attached to the 0th branch of CAMAC, and outputs the execution result to the error output stream. Thus, the sphereoper utility can be used to implement some of the actions described in the supervisor's sv.conf(5) configuration file. The default behavior of the sphereoper utility is modified by the command line switches above. The sphereoper utility returns zero if successful and positive otherwise. To measure the speed of execution of CAMAC commands, a custom interrupt handler CAMAC speedtest was also implemented (for more information about testing the DAQ SPHERE system on the bench, see below), which, for each processed interrupt from CAMAC, executes the configured number of times the tested CAMAC command (selected by changing the source file speedtest.c ). The speedtest loadable module is configured by the stconf(8) utility and controlled by the sphereoper(8) utility (only start, stop, status, and cntcl values ​​of the first positional argument are supported).

Compared to the sphereconf (8) utility, the stconf (8) configuration utility has an additional optional command line switch -n # for transferring specific information to the loadable module, indicating the number of repetitions of the CAMAC command being tested, by default equal to 10, otherwise similar to the latter.

The DAQ SPHERE system uses (in a non-distributed, i.e., executed entirely on one computer, configuration) at least a working module writer(1), a service module bpget(l) and (optional) control modules - supervisor sv(l) and module a graphical representation of the alarm(1) system log from the session-independent set of software modules provided by the qdpb system. Next, we will consider software modules specific to the DAQ SPHERE system.

The statistics collector in the current implementation is called statman and, in terms of the qdpb system, is a working module, a consumer of a packet stream that accumulates data in shared memory in a form convenient for use by software data presentation modules (see below), and has the following command interface: statman [- o] [-b bpemstat [-е] ] [-c(- runcffile )]. [-s(- cellcffile )J [-k(- knobjcffile )] [-i(- cleancffile )] [-p(- pidfile )]

By default, the statman module reads packets from the standard input stream, in accordance with the default configuration files used, collects information from the packet.data body of each incoming packet and accumulates it in shared memory. When started, the statistics collector reads configuration files in the formats RVN.conf(5), cell.conf(5), knobj.conf(5) and clean.conf(5) (see paragraph P.3) and initializes internal arrays of structures accordingly pdat, cell, knvar, knfun, knobj; runs a creation cycle on all initialized known objects and generates the PR0G_BEG event, after which it reads packets from the standard input stream and for each received packet increases the global counter corresponding to its type of event and runs a cycle of calculating results on all initialized cells and a filling/clearing cycle on all initialized ones known objects. Upon receiving an EOF end-of-file status on standard input or a SIGTERM signal, a PR0G_END event is generated, so aborting with a SIGKILL signal is not recommended. The PR0G_BEGIN and PR0G_END events also trigger a calculation cycle for all initialized cells and a fill/clear cycle for all initialized known objects.

The default behavior of the statman module is modified by the command line switches above.

The statman module returns zero if successful and positive otherwise.

The statman module ignores the SIGQUIT signal. The SIGHUP signal is used to reconfigure an already running statman module through a new reading of the runcffile, cellcffile and knobjcffile configuration files (however, with the same names as when the module was launched), which leads to a complete clearing of all currently accumulated information and a reset of the results of all computational cells, i.e. completely equivalent to configuration at startup. The SIGINT signal causes a new read of the cellcf file configuration file (with the same name as at startup) without resetting the cells, which can be used to “reprogram” them on the fly. The SIGUSR1 signal clears all accumulated information, including internal global event counters, the SIGUSR2 signal clears accumulated information according to the cleancffile configuration file. Both of these signals also reset the results of all computation cells. The SIGTERM signal must be used to communicate the normal termination request to the module.

The configuration file of known objects of the statman module can contain declarations of only the types supported by the module, currently the following: "hist", "hist2", "cnt", "coord" and "coord2" (see section II.3 for more details). For each line of data in such a file, the first (name), third (type), fifth (filling event), sixth (filling condition) and seventh (filling event) fields have their standard value for the knobj.conf(5) format. The fields representing the arguments of the create (second), fill (fourth), clear (eighth), and destroy (ninth) functions must conform to the programming interface of the corresponding families of well-known functions.

Analysis of sources of systematic errors

The text data representation module is designed for text visualization of information accumulated in shared memory by the statistics collector. It is called cntview and has the following command interface: cntview [-k(-I knobjconffile )] [-p(- pidfile )] [ sleeptime.

By default, the cntview module reads the data accumulated in shared memory by the statman(l) statistics collector, interprets it according to the default configuration file in knobj.conf(5) format, and outputs its text (ASCII) representation to the error output stream.

The default behavior of the cntview module is modified by the command line switches above. The cntview module returns zero if successful and positive otherwise. The cntview module ignores the SIGQUIT signal. The SIGHUP signal is used to reconfigure an already running cntview module by reading the configuration file again (but with the same name as when the module was started). The SIGUSR1 signal pauses and the SIGUSR2 signal resumes reading and displaying information from shared memory. SIGINT redirects the next batch of data to a printer with a compiled name through the Irg(1) utility. The SIGTERM signal must be used to convey a normal termination request to the module. The configuration file of known objects of the cntview module can contain declarations only of the type "dent" supported by the module (see paragraph II.3 for more details). For a known object "dent", the first (name), third (type), fifth (filling event), sixth (filling condition) and seventh (filling event) fields of the data line have their standard value for the knobj.conf(S) format, then how the fields representing the arguments of the create (second), fill (fourth), clear (eighth), and destroy (ninth) functions must conform to the programming interface of the corresponding family of known functions. For example, the declaration of one known object of type "dent" is written as follows: Obj0041 41;shmid;semid dent 41;3;semid;type_ULong;nht,type_String;4;cnt21:cnt22:cnt23 \ DATA_DAT_0 - NEVERMORE gen prescfg(l) utility (see section II.3) generates the declaration of the known object "dent" given above from a prototype of the following form: dent 41 1 -1 shmid semid 3 ULong nht 4 cnt%2lN DAT_0 - N The utility for monitoring loaded OS kernel modules is called watcher and has the following command interface: watcher [-b # ] [-p(- pidfile )] [ sleeptime ] By default, the watcher utility collects status information (by calling oper() with the HANDGETSTAT subfunction) from the user interrupt handler at intervals of 60 seconds -MAK, attached to the 0th branch of CAMAC, analyzes the state of the latter, taking into account previously received similar information, and issues error messages to the error output stream. Thus, the watcher utility can be used in conjunction with the alarm (1) system log graphical representation module to report some errors in the SPHERE DAQ system. The default behavior of the watcher utility is modified by the command line switches above. The watcher utility returns zero if successful and positive otherwise. The watcher utility ignores the SIGHUP, SIGINT, and SIGQUTT signals. Signal SIGUSR1 pauses and signal SIGUSR2 resumes collecting information. The SIGTERM signal must be used to communicate the normal termination request to the module. To control the SPHERE DAQ system, the supervisor sv(l), described in paragraph II.2, can be used. It is also possible to directly, without the help of a supervisor, execute with the make (1) utility the same commands of the target operator from the supervisor's configuration file sv.conf. Let us describe the purpose of the main operator commands: load - loading and configuring loadable OS kernel modules - branchpoint branchpoint (4) and the user interrupt handler CAMAC sphere (4), launching the bpget(l) service module and attaching it (in the BPRUN state) to the branchpoint , initialization of CAMAC equipment. unload (reverse to load command) - deinitialization of the CAMAC hardware, completion of the bpget(l) module, unloading the branch point and the custom CAMAC interrupt handler, loadw - launching the working module writer (1) with a request to enter the necessary parameters and a reminder about the possibility of entering optional ones and joining it (in BPSTOP state) to the branch point. unloadw (reverse command to loadw) - termination of the writer module (1). loads - launches the working module statman(l) and attaches it (in the BPSTOP state) to the branch point. unloads (reverse command to loads) - termination of the statman module (1). loadh - launching the histview (1) graphical data presentation module using the xterm(l) utility in a separate window of the XII graphic system. unloadh (reverse command to loadh) - termination of the histview module (1). loadc - launching the text data representation module cntview (1) using the xterm(l) utility in a separate window of the XII graphic system. unloadc (reverse command to loadc) - termination of the cntview module (1). start_all - changes the state of all connections to the branch point to BPRUN. stop_all (reverse command to start_all) - changes the state of all connections to the branch point to BPSTOP. init - initialization of CAMAC equipment (it must be executed, for example, after turning on the power of the readable crates, also included in load). finish (reverse to init command) - deinitialization of CAMAC equipment (must be performed, for example, before turning off the power, also included in unload). continue - start processing CAMAC interrupts and launch the watcher utility. pause (reverse to continue command) - ends the watcher utility and stops processing CAMAC interrupts. cleanall - clearing all information accumulated in shared memory by the statman module (1). clean - clearing information accumulated in shared memory by the statman module (1), in accordance with the configuration file specified when starting the module in the clean.conf(5) format. pauseh (reverse to conth command) - pauses data visualization by the histview module (1). pausec (reverse command to contc) - pauses data visualization by the cntview module (1). conth - continuation of data visualization by the histview module (1). contc - continuation of data visualization by the cntview module (1). status - outputs a summary of the status of loaded DAQ SPHERE system elements to the log files of the syslogd(8) daemon. seelog - start viewing messages from the DAQ SPHERE system arriving in the log files of the syslogd(8) daemon using the tail(l) utility. confs - suspending data visualization by the histview (1) and cntview (1) modules, reconfiguring the statman (1), histview (1) and cntview (1) modules, continuing data visualization (used after changing the corresponding configuration files). The DAQ SPHERE system currently uses the following free software packages from third-party manufacturers (in addition to those “inherited” from the qdpb system): SATAS package - implementation of the CAMAC service subsystem. ROOT package - used as an API for graphical visualization of histograms to implement the histview (1) data presentation module.

Golyshkov, Vladimir Alekseevich

1972

/

June

Current state of physics and technology for producing beams of polarized particles

Contents: Introduction. Spin state of the particle. Principles of obtaining polarized ions. Atomic beam method. Dissociation of hydrogen molecules. Formation of a free atomic beam. Hydrogen and deuterium atoms in a magnetic field. Separating magnet. Radio frequency transitions. Radiofrequency transitions in a weak field. Radiofrequency transitions in a strong field. Current installations. Ionization of an atomic beam. Ionizer with a weak magnetic field. Ionizer with a strong magnetic field. Obtaining negative ions by recharging positive polarized ions. Ionization by heavy particles. Lamb's method. Energy levels of hydrogen and deuterium atoms with n= 2 in a uniform magnetic field. Seasons of life. Polarization in a metastable state. Recharging processes. Obtaining negative ions. Obtaining positive ions. Methods for increasing beam polarization. Source of negative polarized ions. Measuring ion polarization. Fast ions. Slow ions. Sources of polarized helium-3 and lithium ions. Polarized singly charged helium-3 ions. Sources of polarized lithium ions. Magnetized single crystal as a polarization donor. Injection of polarized ions into the accelerator. Cockcroft-Walton accelerator and linear accelerator. Van de Graaff accelerator. Tandem accelerator. Cyclotron. Accumulation of polarized ions. Acceleration of polarized ions. Cyclotron. Synchrocyclotron. Phasotron with spatial variation of magnetic field. Synchrotron. Achievements of individual laboratories. Berkeley, California. Los Alamos. Conclusion. Cited literature.