Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 51 (2018)

Production of very neutron-rich nuclei via two-proton knockout
reaction with deuterium operation of MINOS
M. Miwa,∗1,∗2 T. Uesaka,∗2 Y. Kubota,∗2 H. Wang,∗2 H. Otsu,∗2 P. Doornenbal,∗2 A. Obertelli,∗3,∗4,∗2
N. Achouri,∗5 H. Baba,∗2 F. Browne,∗2 D. Calvet,∗4 F. Château,∗4 S. Chen,∗6,∗2 N. Chiga,∗2 A. Corsi,∗4M. L. Cortés,∗2 A. Delbart,∗4 J.-M. Gheller,∗4 A. Giganon,∗4 A. Gillibert,∗4 C. Hilaire,∗4 T. Isobe,∗2T. Kobayashi,∗7 V. Lapoux,∗4 H. N. Liu,∗4,∗8 T. Motobayashi,∗2 I. Murray,∗9,∗2 V. Panin,∗2 N. Paul,∗4W. Rodriguez,∗10,∗2 H. Sakurai,∗11,∗2 M. Sasano,∗2 D. Steppenbeck,∗2 L. Stuhl,∗12 Y. L. Sun,∗4 Y. Togano,∗13,∗2K. Wimmer,∗11,∗2 K. Yoneda,∗2 O. Aktas,∗8 T. Aumann,∗3 L. X. Chung,∗14 F. Flavigny,∗9 S. Franchoo,∗9I. Gasparic,∗15,∗2 R.-B. Gerst,∗16 J. Gibelin,∗5 K. I. Hahn,∗17 D. Kim,∗17 T. Koiwai,∗11 Y. Kondo,∗18P. Koseoglou,∗3,∗19 J. Lee,∗20 C. Lehr,∗3 B. D. Linh,∗14 T. Lokotko,∗20 M. MacCormick,∗9 K. Moschner,∗16T. Nakamura,∗18 S. Y. Park,∗17 D. Rossi,∗19 E. Sahin,∗21 D. Sohler,∗22 P.-A. Söderström,∗3 S. Takeuchi,∗18
H. Törnqvist,∗19 V. Vaquero,∗23 V. Wagner,∗3 S. Wang,∗24 V. Werner,∗3 X. Xu,∗20 H. Yamada,∗18 D. Yan,∗24Z. H. Yang,∗2 M. Yasuda,∗18 and L. Zanetti∗3The production of neutron-rich nuclei through onenucleon knockout (p, 2p) reactions has been successfully
demonstrated with the MINOS setup.1) In future RIBF
experiments, a method to remove more than one protonwith a reasonable rate will be required for the production of more neutron-rich nuclei. At present there isno consensus on the best reaction for two-proton removal. In this work, the performance of the (d, 3pn)
reaction with the MINOS setup as a candidate of thetwo-proton knockout driver in future RIBF experiments
is discussed. the results of a recent nuclear transmutation experiment at RIBF2) show an encouraging indication that the production cross sections of neutron-richnuclei are larger with a deuteron target than with a proton target. In this report, cross sections of the (p, 3p)
and (d, 3pn) reactions on a 58 Ti beam are shown anddiscussed.
The experiment was carried out using the SAMURAI
spectrometer after the third SEASTAR campaign3) inMay 2017. A secondary cocktail beam including 58 Ti
was produced with projectile fragmentation reactionsof a primary 70 Zn beam at 345 MeV/u impinging on aberyllium target. The experimental setup was the sameas that of the SEASTAR experiment, except for thetarget material. The target was liquid deuterium witha thickness of 2.6 g/cm2 . The 58 Ti beam with an initialenergy of 240 MeV/u loses its energy by 90 MeV/uin the target. The measured cross section is the one
averaged over 150–240 MeV/u. The secondary beamand fragments were identiﬁed event by event using the∆E–TOF–Bρ method.
Figure 1 summarizes preliminary results of the crosssection ratio for a deuteron target to a proton target.
The ratio of interaction cross sections is greater than
one and less than two. This is due to a well-known
eclipse eﬀect proposed by Glauber.4) The result for
two-proton removal cross sections shows a Frisigniﬁcantly
Jan 19 15:53:06 2018
larger value of ∼ 3, while that for one-proton removal
is not so diﬀerent from the interaction cross section result. This fact implies possible advantages of a deuterontarget to produce neutron-rich nuclei.
Data for other isotopes in the cocktail beam will provide us with a global feature of the cross section ratio and reaction analyses for the data will reveal why
a deuteron target is so eﬃcient removing two protons
from neutron-rich nuclei.

∗1

Department of Physics, Toho University
RIKEN Nishina Center∗3 Institut für Kernphysik, Technische Universität Darmstadt∗4 IRFU, CEA, Université Paris-Saclay∗5 LPC Caen, ENSICAEN, Univeristé de Caen, CNRS/IN2P3∗6 Department of Physics, Peking University∗7 Department of Physics, Tohoku University∗8 Department of Physics, Royal Institute of Technology∗9 IPN Orsay, CNRS, Univ. Paris Sud, Univ. Paris Saclay∗10 Universidad Nacional de Colombia∗11 Department of Physics, The University of Tokyo∗12 Center for Nuclear Study, The University of Tokyo∗13 Department of Physics, Rikkyo University∗14 Institute for Nuclear Science & Technology, VINATOM∗15 Rudjer Boskovic Institute∗16 Institut für Kernphysik, Universität zu Köln∗17 Ewha Womans University∗18 Department of Physics, Tokyo Institute of Technology∗19 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗20 Department of Physics, The University of Hong Kong
∗21 Department of Physics, University of Oslo
∗22 MTA Atomki∗23 Instituto de Estructura de la Materia, CSIC
∗24 Institute of Modern Physics, Chinese Academy of Sciences

σd / σp∗2543210

ary

reliminVery pσtotalσ-1p

σ-2pFig. 1. Ratio of cross sections for a deuteron target to aproton target. σtotal : interaction cross section (σd /σp ).
σ−1p : one proton removal cross section. σ−2p : twoproton removal cross section.

References
1) A. Obertelli et al., Eur. Phys. Jour. A 50, 8 (2014).
2) H. Wang et al., Phys. Lett. B 754, 104 (2016).
3) P. Doornenbal, A. Obertelli, RIKEN Proposal for Scientific Program (2013).
4) R. J. Glauber, Phys. Rev. 100, 242 (1955).

- 40 -