Fabrication of thin Nb target for lifetime measurements of short lived excited nuclear states

摘要

The quality of target foils often plays an important role in the success of nuclear physics experiments. Specially, in an experiment intended to measure the level lifetimes of short lived excited nuclear states with Doppler shift attenuation method (DSAM), an isotopically enriched thin target on appropriately thick backing foil of high-Z material is preferentially required. In the present work, a thin (thickness ≈ 0.9 mg/cm~2) mono-isotopic Nb target on thick (thickness ≈ 9.2 mg/cm~2) lead backing has been prepared using rolling technique at the Inter University Accelerator Center (IUAC), New Delhi. To meet the important criteria of sufficient thickness and proper sticking of two foils without any air gap in-between, some novel methods like heating of stainless steel (SS) pack before rolling, frequent change of rolling pack, use of alcohol during rolling, unidirectional rolling under low pressure specially for rolling lead foil and the composite target, were adopted. The quality check of prepared target foil was done with the energy dispersive X-ray fluorescence (EDXRF) technique. The prepared target has been successfully used in a recent DSAM lifetime measurement experiment at IUAC, New Delhi.