Discovery of 68Br in secondary reactions of radioactive beams

K Wimmer,R Wadsworth,G De Angelis,L Sinclair,J Gerl,A Obertelli,R Gernhäuser,R Taniuchi,A Algora,D Lubos,P Davies,S Koyama,P Doornenbal,S Chen,A Boso,B Rubio,D Steppenbeck,G De France,T Motobayashi,H Baba,S Nagamine,P Aguilera,A Corsi,Takeshi Saito ,T Arıcı ,Β Blank ,H Sakuraï ,D T Doherty ,Takashi Ando ,M Nııkura ,W Körten ,E Šahin ,D G Jenkins ,M Zielińska

doi:10.1016/j.physletb.2019.06.014

Abstract

The proton-rich isotope 68Br was discovered in secondary fragmentation reactions of fast radioactive beams. Proton-rich secondary beams of 70,71,72Kr and 70Br, produced at the RIKEN Nishina Center and identified by the BigRIPS fragment separator, impinged on a secondary 9Be target. Unambiguous particle identification behind the secondary target was achieved with the ZeroDegree spectrometer. Based on the expected direct production cross sections from neighboring isotopes, the lifetime of the ground or long-lived isomeric state of 68Br was estimated. The results suggest that secondary fragmentation reactions, where relatively few nucleons are removed from the projectile, offer an alternative way to search for new isotopes, as these reactions populate preferentially low-lying states.

Highlights

The proton-rich isotope 68Br was discovered in secondary fragmentation reactions of fast radioactive beams
The results suggest that secondary fragmentation reactions, where relatively few nucleons are removed from the projectile, offer an alternative way to search for new isotopes, as these reactions populate preferentially low-lying states
New isotopes have been mainly discovered by projectile fragmentation or fission of high intensity primary beams [4,5,6,7,8,9,10,11]

Summary

Introduction

The proton-rich isotope 68Br was discovered in secondary fragmentation reactions of fast radioactive beams. In a search for new isotopes, proton-rich N = 33 nuclei were produced at the NSCL [16], and 68Br remained unobserved suggesting that the isotope is unbound with a lifetime significantly shorter than the flight time through the separator.

Results

Conclusion