Eur. Phys. J. A (2007) 31: 155-162
https://doi.org/10.1140/epja/i2007-10001-y

Regular Article - Nuclear Structure and Reactions

Center-of-mass effects in electromagnetic two-proton knockout reactions

¹ Dipartimento di Fisica Nucleare e Teorica, Università degli Studi di Pavia and Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, I-27100, Pavia, Italy
² Dipartimento di Fisica, Università degli Studi di Trento and Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Trento, I-38100, Povo (Trento), Italy
³ European Center for Theoretical Studies in Nuclear Physics and Related Areas, I-38100, Villazzano (Trento), Italy

^* e-mail: Carlotta.Giusti@pv-infn.it

Received: 18 January 2007
Accepted: 19 January 2007
Published online: 8 February 2007

Abstract

The role of center-of mass (CM) effects in the one-body nuclear current in the description of electromagnetically induced two-nucleon knockout reactions is discussed in connection with the problem of the lack of orthogonality between initial bound states and final scattering states obtained by the use of an energy-dependent optical model potential. Results for the cross-sections of the exclusive ¹⁶O(e, e'pp)¹⁴C and ¹⁶O(γ, pp)¹⁴C knockout reactions in different kinematics are presented and discussed. In super-parallel kinematics CM effects produce a strong enhancement of the ¹⁶O(e, e'pp)¹⁴C_g.s. cross-section which strongly reduces the destructive interference between the one-body and Δ-current and the sensitivity to the treatment of the Δ-current found in previous work.