Conzett, H. E.

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Lawrence Berkeley National LaboratoryRecent WorkTitleTHE VECTOR ANALYZING POWER IN ELASTIC DEUTERON-EEUTERON SCATTERING BETWEEN 20 and 20 MeVPermalinkhttps://escholarship.org/uc/item/1rf2w0p1AuthorConzett, H. E.Publication Date1975-06-01eScholarship.org Powered by the California Digital LibraryUniversity of CalifornialJ ..; Presented at the 4th International Symposium on Polarization Phenomena In Nuclear Reactions, Z~rich, Switzerland, August 25 - 29, 1975 LBL-4049 ... ' THE VECTOR ANALYZING POWER IN ELASTIC DEUTERON-DEUTERON SCATTERING BETWEEN 20 AND 40 MeV H. E. Conzett, W. Dahme, R. M. Larimer, Ch. Lee mann, and J. S. C. McKee June 1975 Prepared for the U. S. Energy Research and Development Administration under Contract W -7405-ENG-48 For Refer~nce Not to be taken from this room DISCLAIMER This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor the Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or the Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or the Regents of the University of California. ' '.J {I .,. ' - ' •\:' .j g 0 THE VECTOR ANALYZING POWER IN ELASTIC DEUTERON-DEUTERON SCATTERING BETWEEN 20 AND 40 MeV* H. E. Conzett, w. Dahme+, R. M. Larimer, Ch. 'Leemann, * . and J. s. c. McKee Lawrence Berkeley Laboratory, University of California Berkeley, California 94720 LBL-4049 The subject of d-d elastic scattering has not received very much at-tention in the past. The cross sections are quite smooth functions of energy in the region up to 20 MeV where there are the most data available. However, the complexity of the spin structure and the low threshold for inelastic processes has made any meaningful phase-shift analysis impos-sible because of th~ large number of parameters involved even with the restrictive assum~tion of channel-spin conservation 1 >. A resonating-group calculation ) has obtained good agreement with the cross-section data between 5 and 20 MeV, but the use of a purely central nucleon-nucleon potential precludes the prediction of any spin-polarization observables. From an experimental point of view, the polarization experiments in elastic d-d scattering have raised a qualitative~question. Previous measurements of the vector analyzing power iT11 in d-d scattering have been made at several energies below 12 Mev.I,3) and at 21.4 Mev4 >. Non-zero but very small values of iT11 were obtained, reaching a maximUm value of about 0.04 at 21.4 MeV. These values are almost an order of magnitude smaller than the nucleon and deuteron vector analyzing powers tound in other elastic processes involving few nucleon systems, e.g. p + 2 H, 3He, 4 He and a + 3He, 4 He. Since sizable contributions of s, P, and D-waves were required to fit the d-d cata1 ' 2 ), ~he ~a~her insignificant polarization effects could not be explained as a con-sequence of a predominance of s-wave scattering. Thus, its reason remained unexplained. ~ We have extended the measurements of vector analyzing powers 'in d-d scattering to 40 MeV to examine whether or not its anomalously small value persists at these higher energies. Also, another determination near 20 MeV was desired, since the older measurement at 21.4 MeV was rather uncertain because of lack of knowledge of the beam polarization. We used the axially injected vector-polarized deuteron beam from the Berkeley 88-Inch Cyclotron. Left-right asymmetry data were taken simultaneously at two angles separated by 20°, using pairs of ~E-E sili-con detector telescopes. A polarimeter, consisting of a gas target and a pair of AE-E counter telescopes, was placed downstream of the main scattering chamber and provided continuous monitoring of the beam polari-~ation. The analyzer used was 4He, whose vector analyzing power in d- 4 He elastic scattering has been measured in detail 5 >. The differential cross section for vector-polarized deuterons is given by ace> = a0 (8) [1 + 2 (it11 > (iT11>], Cl) where a 0 (8) is the differential cross-section for unpolarized deuterons and itu is the beam polarization. A left-right asymmetry measurement gives (2) and the simultaneous determination of the beam polarization yields the vector analyzing powers iT11 • Figure 1 shows our data at Ed= 20, 30, and 40 MeV; the particle symmetry requires that iTu (6) = - iT11 (1T-6}. Our 2Q-MeV values are a factor of two larger than the previous results at 21.4 MeV, and clearly the vector analyzing powers increase rapidly with increasing energy. These values, when compared with the analyzing powers in a-p elastic-scattering measured at comparable center-of-mass energies 6 >, can no longer be consider~d anomalously small. · 0.30 ' ' i •20MeV o30MeV •40MeV 0.225 •• 4 I i 1 0.15 I f I • • • • I D • .075 I • .; I D • • • • .. -O.OOt-------------1----'---1 I • & -0.75 t f 20 40 60 eo 100 Center of moss angle .. ,. ...... -References * + * Work performed under the auspices of the u. s. Energy Research and Development Administration. Sektion Physik ~er Universitat MUnchen, 8046 Garching, Germany. University of Manitoba, Winnipeg, Manitoba, Canada. 1} G. R. Plattner and L. G. Keller, Phys. Letters !Q!, (1969). 327; P. D. Lien, Nucl. Phys. ~ (1972) 375; H. o. Meyer and P. Schiemenz, Nucl. Phys. Al97 (1972) 259. 2} F. s. Chwieroth, Y. c. Tang, and D. R. Thompson, Nucl. Phys. Al89 (1972) 1. 3) W. GrUebler, V. KOnig, R. Risler, P. A. Schmelzbach, R. E. White, and P. Marmier, Nucl. Phys. Al93 (1972) 149. 4) J. Arvieux, J. Gouderques, B. Mayer, and A. Papineau, Phys. Let~ers 22 (1966) 610. 5) H. E. Conzett, w. Dahme, Ch. Leemann, J. A. Macdonald and J. P. Meulders, Fourth Polarization Symp. 6) J. s. C. McKee, H. E. Conzett, R. M. Larimer and Ch. Leemann, Phys. Rev. Lett. ~ (1972) 1613. ., l I ., , u v ---------LEGAL NOTICE---------.--. This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Energy Research and Development Administration, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. ,.. ~ ... ~ .. TECHNICAL INFORMATION DIVISION LAWRENCE BERKELEY LABORATORY UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA 94720 #.'1 . .. .............. 

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THE VECTOR ANALYZING POWER IN ELASTIC DEUTERON-EEUTERON SCATTERING BETWEEN 20 and 20 MeV

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THE VECTOR ANALYZING POWER IN ELASTIC DEUTERON-EEUTERON SCATTERING BETWEEN 20 and 20 MeV

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