TRIAC Progress Report - KEK

corresponds to an excited state of 22.4 MeV in 10 Be, which was also reported as a
proton/triton decaying state both in the neutron capture experiment of 9 Be and in the
resonant particle decay spectroscopy of 7 Li + 7 Li. It has been recently suggested that the
state might be a candidate of a coexisting cluster state with cluster structures of (α+t+t)
and (α+α+n+n) [3-8], which are of great importance not only for understanding the
clustering phenomena in neutron rich nuclei but also for an accurate estimate of the
reaction rate linked with such a state in the process of nucleosynthesis. The aim of this
experiment is to determine the spin and parity of this state, by using the thick-target
resonance elastic scattering of deuteron by 8 Li as shown in Fig. 3-5.
Fig. 3-5. Experimental set-up and principle of the thick-target elastic scattering method for
resonance-searching.
Following the PAC recommendation, a feasibility test for this measurement has
been performed for 3 days. A schematic figure for the experimental set-up and the
measurement principle is shown in Fig. 3-5. An elastic scattering with thick target was
employed in the inverse kinematics to search for the resonance states. The 8 Li beam of
0.94 MeV/nucleon with an intensity of 4.5 kpps passed through a time pick-up detector
(C-foil + Micro-Channel Plate (MCP) in Fig. 3-5) bombarded to the CD2 target of 2.6
mg/cm 2 in thickness. The energy of the scattered particles was measured by a set of
Solid State Detectors (SSD), and their time-of flight (TOF) between the MCP and SSD
was also measured. As shown in Fig. 3-6, where the correlations between the energy
and the TOF for detected particles were plotted, scattered deuterons were successfully
identified. In the figure were also observed tritons, 8 Li particles passed through
pin-holes on the target, and α-particles from decaying 8 Li, in addition to deuterons.
These particles were well resolved. Based on the present result, we can conclude that
the thick-target elastic scattering method for resonance-searching is feasible with the
beam intensity of 8 Li presently available at TRIAC (i.e. higher than 100 kpps). For
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