Abstract
The helicity dependences of the differential cross sections for the semi-inclusive γ 3He → π0 X and γ 3He → π± X reactions have been measured for the first time in the energy region 200 < E γ 450 MeV. The experiment was performed at the tagged photon beam facility of the MAMI accelerator in Mainz using a longitudinally polarised high-pressure 3He gas target. Hadronic products were measured with the large-acceptance Crystal Ball detector complemented with additional devices for charged-particle tracking and identification. Unpolarised differential cross sections and their helicity dependence are compared with theoretical calculations using the Fix-Arenhövel model. The effect of the intermediate excitation of the Δ(1232) resonance can be clearly seen from this comparison, especially for the polarised case, where nuclear effects are relatively small. The model provides a better theoretical description of the unpolarised charged pion photoproduction data than the neutral pion channel. It does significantly better in describing the helicity-dependent data in both channels. These comparisons provide new information on the mechanisms involved in pion photoproduction on 3He and suggest that a polarised 3He target can provide valuable information on the corresponding polarised quasi-free neutron reactions.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
J. Ahrens et al., Phys. Rev. Lett. 88, 232002 (2002).
J. Ahrens et al., Eur. Phys. J. A 44, 189 (2010).
W.J. Briscoe et al., Phys. Rev. C 86, 065207 (2013).
P. Aguar Bartolomé et al., Phys. Lett. B 723, 71 (2013).
H. Arenhövel, A. Fix, Phys. Rev. C 72, 064004 (2005).
A. Fix, H. Arenhövel, Phys. Rev. C 72, 064005 (2005).
H. Herminghaus et al., IEEE Trans. Nucl. Sci. 30, 3274 (1983).
H. Kaiser et al., Nucl. Instrum. Methods A 593, 159 (2008).
K. Aulenbacher et al., Nucl. Instrum. Methods A 391, 498 (1997).
V. Tioukine, K. Aulenbacher, N. Riehn, Rev. Sci. Instrum. 82, 033303 (2011).
I. Preobrajenski, PhD thesis, University of Mainz (2001).
H. Olsen, L. Maximon, Phys. Rev. 114, 887 (1959).
I. Anthony et al., Nucl. Instrum. Methods A 301, 230 (1991).
S.J. Hall et al., Nucl. Instrum. Methods A 368, 698 (1996).
J.C. McGeorge et al., Eur. Phys. J. A 37, 129 (2008).
S. Schumann et al., Eur. Phys. J. A 43, 269 (2010).
J. Krimmer et al., Nucl. Instrum. Methods A 648, 35 (2011).
A. Starostin et al., Phys. Rev. C 64, 055205 (2001).
D.P. Watts, Calorimetry in Particle Physics: Proceedings of the 11th International Conference (World Scientific, Singapore, 2005) p. 560.
G. Audit et al., Nucl. Instrum. Methods A 301, 473 (1991).
J. Ahrens et al., Phys. Lett. B 624, 173 (2005).
F. Zehr et al., Eur. Phys. J. A 48, 98 (2012).
D. Drechsel, S. Kamalov, L. Tiator, Eur. Phys. J. A 34, 69 (2007).
J. Ahrens et al., Eur. Phys. J. A 34, 11 (2007).
F. Carbonara et al., Nuovo Cimento A 36, 219 (1976).
C. Ciofi degli Atti, S. Scopetta, Phys. Lett. B 404, 223 (1997).
J.L. Friar et al., Phys. Rev. C 42, 2310 (1990).
V. Baru et al., Eur. Phys. J. A 16, 437 (2003).
C. Lazard, Z. Maric, Nuovo Cimento A 16, 605 (1973).
C.A. Engelbrecht, Phys. Rev. 133, B988 (1964).
J.M. Laget, Nucl. Phys. A 194, 81 (1972).
M. Egorov, A. Fix, Phys. Rev. C 88, 054611 (2013).
Author information
Authors and Affiliations
Consortia
Corresponding author
Additional information
Communicated by P. Rossi
Rights and permissions
About this article
Cite this article
A2 Collaboration., Costanza, S., Mushkarenkov, A. et al. Helicity dependence of the γ 3He → πX reactions in the Δ(1232) resonance region. Eur. Phys. J. A 50, 173 (2014). https://doi.org/10.1140/epja/i2014-14173-y
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1140/epja/i2014-14173-y