Decay Studies of Exotic Heavy Nuclei with RISING at the GSI Fragment Separator

Lead Research Organisation: University of Surrey
Department Name: Nuclear and Radiation Physics

Abstract

1) Shell structure in atomic nuclei is the fundamental basis for our understanding of nuclear matter. This is the major scientific input required to understand the creation of elements heavier than iron through nuclear reactions in stars. 2) Metastable excited nuclear states (known as 'isomers') can exists in certain nuclear species due to their constituent protons and neutrons being arranged in different configurations to the lowest energy configuration(known as the 'ground state'). These isomers can be useful both as experimental 'tags' which allow us to identify given nuclei and also as tests of current descriptions of the fundmental interactions which hold the nucleus together. 3) Neutron-rich systems (i.e. nuclei with more neutrons compared to the radioactively stable isotopes of these elements) are very hard to access experimentally. One of the most promising ways of looking at many neutron-rich nuclei for the first time is to use the technique of 'projectile fragmentation reactions' where neutron-rich nuclei can be created in collisions between very high-energy nuclear beams and stationary target foils. 4) A series of magnets can be use as a 'mass-separator' to identify different nuclear species by their individual mass and charge (which is related to the proton number, Z). The Fragment Separator (FRS)based at the GSI heavy-ion laboratory in Darmstadt Germany, has been specifically developed to allow these types of measurements for high-energy nuclear collisions to identify for a host of new and exotic, heavy neutron-rich radioactive nuclei. 5) This grant asks for the funds to examine the internal structure of some highly exotic nuclei with a significant excess of neutrons compared to the typical forms of these elements seen on earth. This information allows us see if the usual shell structure which occurs in stable nuclei is modified for isotopes where extra neutrons added. 6) In order to make these measurements we need to be able to detect a number of
 
Description The grant allowed the first measurements of the internal structure in a range of exotic forms of nuclear matter. These includes the lightest atoms of the elements Tc and Nb and the heaviest forms of the element Mercury.
Exploitation Route Nuclear data and spectroscopic information.
Input for nuclear models and designers of radiation monitoring systems.
Input into nuclear astrophysical research theories.
Development of nuclear analytical techniques which might have future application in nuclear forensics and analysis.
Sectors Education,Electronics,Energy,Environment,Culture, Heritage, Museums and Collections,Security and Diplomacy

URL http://gammapool.lnl.infn.it/index/home/Gammapool_10_years.pdf
 
Description The results of the RISING experiments have been used to provide a number of 'first spectroscopy' examples in a range of nuclei with unusual proton to neutron ratios. In particular, the isomer spectroscopy of the odd-odd, N=Z nucleu 82Nb and 86Tc has provided new information in competition between T=1 and T=0 proton-neutron pairing modes in atomic nuclei. The information on isomeric decays in N=126 isotones has been extended from the Z=80 case (206Hg) down to 203Ir (Z=77), which represents a real breakthrough in this region of the nuclear chart. Reaction theory based on nucleon knock-out from well defined shell model orbits (specifically high-j orbits) has been studied in detail and comapred with measured isomeric production ratios in these nuclei as function of both nuclear angular momentum (Spin) and number of nucleons abraded/ablated in projectile fragmentation reactions. Research in this area also provided platform for UK comment on Fukushima nuclear power issues and informed public debate on nuclear power in the UK, in particular associated with measurement and safety issues on nuclear fission waste products (in March 2011).
First Year Of Impact 2007
Sector Education,Energy,Environment,Security and Diplomacy
Impact Types Societal,Policy & public services