Experimental Investigation of Suppression Factors in Knockout and (p,2p) Reactions
ORAL
Abstract
The knockout of nucleons from nuclei is a powerful tool to investigate nuclear structure. However, when comparing the cross sections of one-nucleon knockout reactions to theory, one finds a systematic overestimation, which can be corrected for using a reduction factor R.
The observed isospin dependence of the reduction factor R is a longstanding challenge to the nuclear physics community. A conclusive explanation is still under active debate, however the discrepancy is expected to either originate from the nuclear structure part or the reaction part of the calculation, or possibly even a mix of both.
The analysis of an experiment at RIKEN, RIBF is presented here. It includes the one-proton removal reaction from 38,48,54Ca beams on a 1g/cm2 C target, as well as the simultaneous (p,2p) and knockout reaction on a 1.229g/cm2 CH2 target utilising the same settings. This setup a direct comparison of the reactions, and reaction calculations, using the same nuclear structure input. The three beams cover the neutron-deficient, stable and neutron-rich side, yielding a trend with isospin for both one-nucleon knockout as well as (p,2p) reactions. The difference of both trends allows an assignment of the isospin dependence to either originate from the nuclear structure part or the reaction mechanism part of the theoretical calculations.
The observed isospin dependence of the reduction factor R is a longstanding challenge to the nuclear physics community. A conclusive explanation is still under active debate, however the discrepancy is expected to either originate from the nuclear structure part or the reaction part of the calculation, or possibly even a mix of both.
The analysis of an experiment at RIKEN, RIBF is presented here. It includes the one-proton removal reaction from 38,48,54Ca beams on a 1g/cm2 C target, as well as the simultaneous (p,2p) and knockout reaction on a 1.229g/cm2 CH2 target utilising the same settings. This setup a direct comparison of the reactions, and reaction calculations, using the same nuclear structure input. The three beams cover the neutron-deficient, stable and neutron-rich side, yielding a trend with isospin for both one-nucleon knockout as well as (p,2p) reactions. The difference of both trends allows an assignment of the isospin dependence to either originate from the nuclear structure part or the reaction mechanism part of the theoretical calculations.
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Presenters
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Axel Frotscher
Lawrence Berkeley National Laboratory
Authors
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Axel Frotscher
Lawrence Berkeley National Laboratory