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Title: Photo- and electro-disintegration of {sup 3}He at threshold and pd radiative capture

Abstract

The present work reports results for: (1) pd radiative capture observables measured at center-of-mass (c.m.) energies in the range 0--100 keV and at 2 MeV by the TUNL and Wisconsin groups, respectively; (2) contributions to the Gerasimov-Drell-Hearn (GDH) integral in {sup 3}He from the two- up to the three-body breakup thresholds, compared to experimental determinations by the TUNL group in this threshold region; (3) longitudinal, transverse, and interference response functions measured in inclusive polarized electron scattering off polarized {sup 3}He at excitation energies below the threshold for breakup into ppn, compared to unpolarized longitudinal and transverse data from the Saskatoon group. The calculations are based on pair-correlated-hyperspherical-harmonics bound and continuum wave functions obtained from a realistic Hamiltonian consisting of the Argonne {upsilon}{sub 18} two-nucleon and Urbana IX three-nucleon interactions. The electromagnetic current operator includes one- and two- body components, leading terms of which are constructed from the Argonne {upsilon}{sub 18} interaction (specifically, its charge-independent part). Two-body currents associated with {Delta}-isobar degrees of freedom are treated non-perturbatively via the transition-correlation-operator method. The theoretical predictions obtained by including only one-body currents are in violent disagreement with data. These differences between theory and experiment are, to a large extent, removed when two-body currentsmore » are taken into account, although some rather large discrepancies remain in the c.m. energy range 0--100 keV, particularly for the pd differential cross section {sigma}({theta}) and tensor analyzing power T{sub 20}({theta}) at small angles, and contributions to the GDH integral. A rather detailed analysis indicated that these discrepancies have, in large part, a common origin, and can be traced back to an excess strength obtained in the theoretical calculation of the E{sub 1} reduced matrix element associated with the pd channel having L,S,J = 1, 1/2, 3/2. It is suggested that this lack of E{sub 1} strength observed experimentally might have implications for the nuclear interaction at very low energies. Finally, the validity of the long-wavelength approximation for electric dipole transitions is discussed.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Univ. of Pisa (IT)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
755325
Report Number(s):
DOE/ER/40150-1437; JLAB-THY-99-36; nucl-th/9911051
TRN: US0002422
DOE Contract Number:  
AC05-84ER40150
Resource Type:
Journal Article
Journal Name:
submitted to Phys. Rev. C
Additional Journal Information:
Other Information: Submitted to Phys. Rev. C; PBD: 1 Nov 1999
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; HELIUM 3 TARGET; DEUTERIUM TARGET; PHOTONUCLEAR REACTIONS; ELECTRON REACTIONS; PROTON REACTIONS; CAPTURE; BREAKUP REACTIONS; POLARIZED TARGETS; POLARIZED BEAMS; E1-TRANSITIONS

Citation Formats

Viviani, M, Kievsky, A, Marcucci, L E, Rosati, S, and Schiavilla, R. Photo- and electro-disintegration of {sup 3}He at threshold and pd radiative capture. United States: N. p., 1999. Web.
Viviani, M, Kievsky, A, Marcucci, L E, Rosati, S, & Schiavilla, R. Photo- and electro-disintegration of {sup 3}He at threshold and pd radiative capture. United States.
Viviani, M, Kievsky, A, Marcucci, L E, Rosati, S, and Schiavilla, R. 1999. "Photo- and electro-disintegration of {sup 3}He at threshold and pd radiative capture". United States. https://www.osti.gov/servlets/purl/755325.
@article{osti_755325,
title = {Photo- and electro-disintegration of {sup 3}He at threshold and pd radiative capture},
author = {Viviani, M and Kievsky, A and Marcucci, L E and Rosati, S and Schiavilla, R},
abstractNote = {The present work reports results for: (1) pd radiative capture observables measured at center-of-mass (c.m.) energies in the range 0--100 keV and at 2 MeV by the TUNL and Wisconsin groups, respectively; (2) contributions to the Gerasimov-Drell-Hearn (GDH) integral in {sup 3}He from the two- up to the three-body breakup thresholds, compared to experimental determinations by the TUNL group in this threshold region; (3) longitudinal, transverse, and interference response functions measured in inclusive polarized electron scattering off polarized {sup 3}He at excitation energies below the threshold for breakup into ppn, compared to unpolarized longitudinal and transverse data from the Saskatoon group. The calculations are based on pair-correlated-hyperspherical-harmonics bound and continuum wave functions obtained from a realistic Hamiltonian consisting of the Argonne {upsilon}{sub 18} two-nucleon and Urbana IX three-nucleon interactions. The electromagnetic current operator includes one- and two- body components, leading terms of which are constructed from the Argonne {upsilon}{sub 18} interaction (specifically, its charge-independent part). Two-body currents associated with {Delta}-isobar degrees of freedom are treated non-perturbatively via the transition-correlation-operator method. The theoretical predictions obtained by including only one-body currents are in violent disagreement with data. These differences between theory and experiment are, to a large extent, removed when two-body currents are taken into account, although some rather large discrepancies remain in the c.m. energy range 0--100 keV, particularly for the pd differential cross section {sigma}({theta}) and tensor analyzing power T{sub 20}({theta}) at small angles, and contributions to the GDH integral. A rather detailed analysis indicated that these discrepancies have, in large part, a common origin, and can be traced back to an excess strength obtained in the theoretical calculation of the E{sub 1} reduced matrix element associated with the pd channel having L,S,J = 1, 1/2, 3/2. It is suggested that this lack of E{sub 1} strength observed experimentally might have implications for the nuclear interaction at very low energies. Finally, the validity of the long-wavelength approximation for electric dipole transitions is discussed.},
doi = {},
url = {https://www.osti.gov/biblio/755325}, journal = {submitted to Phys. Rev. C},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 01 00:00:00 EST 1999},
month = {Mon Nov 01 00:00:00 EST 1999}
}