3He cryogenic target are not very wide spread (see ref.[Gal21] and references therein). Few have been designed for reactions measurements but for high energy beams (particularly for RIKEN) [Ryu05]. There is two 3He target specifically designed for transfer reactions experiments with low-energy (∼ 10 MeV/u) and low-intensity (∼104-106 pps) beams: the HeCTOr target [Gal21] run during the MUGAST-AGATA-VAMOS campaign at GANIL [Ass21] and the recently commissioned CTADIR target [Sed25].
HeCTOr (HeCryogenic Target at Orsay) is based on a permanent flow of saturated 4He coming from a dewar to cool down to 6 K the target cell. This latter is 3 mm thick with an opening angle of 130 degrees on one side and 60 degrees on the other side. It is designed to be operated up to 1 bar and down to 4 K. To handle the pressure, the windows are made of 3.8 um thick Havar and are deformed by 0.7 mm when operated at 1 bar. Under the above conditions, HeCTOr can reach 2 mg/cm2 equivalent thickness of 3He i.e. 4 1020 atoms per cm2.
The goal of the present proposal is to build a new 3He cryogenic target with a complete change of strategy to solve the issues identified with HeCTOr:
- an “online” de-icing protocol will be developed. It is made possible by the use of the cryocooler.
- the target will be refrigerated by use of a pulse-tube type cryocooler: this cryogen-free technique will enhance experimental possibilities with a more compact target system, more portable, easier to integrate and more transparent to gamma-rays.
- new target window material will be investigated with less density and/or lower thickness to improve the energy losses and the straggling of the light recoiling particles.
[Gal21] F. Galtarossa, et al, Nucl. Instr. and Meth. in Phys. Res. A 1018,165830 (2021). https://arxiv.org/pdf/2105.06279.pdf
[Ryu05] H. Ryuto et al., Nucl. Instr. and Meth. in Phys. Res. A 555, 1 (2005).
[Sed25] M. Sedlak et al, Nucl. Instr. and Meth. in Phys. Res. A 1080, 170626 (2025).
HeCTOr (He Cryogenic Target at Orsay)
is based on a permanent flow of saturated 4He coming from a dewar to
cool down to 6 K the target
cell. This latter is 3 mm thick with an opening angle of 130 degrees on one
side and 60 degrees on the other side. It is designed to be operated up to 1
bar and down to 4 K. To handle the pressure, the windows are made of 3.8 um
thick Havar and are deformed by 0.7 mm when operated at 1 bar. Under the above
conditions, HeCTOr can reach 2 mg/cm2 equivalent thickness of 3He
i.e. 4 1020 atoms per cm2.
3He cryogenic target are not very
wide spread (see ref.[Gal21] and references therein). Few have been designed for
reactions measurements but for high energy beams (particularly for RIKEN)
[Ryu05]. The only 3He target specifically designed for transfer
reactions experiments with low-energy (∼ 10 MeV/u) and low-intensity (∼104-106
pps) beams is the HeCTOr target [Gal21] built and run by our consortium during
the MUGAST-AGATA-VAMOS
campaign at GANIL [Ass21] to study the proton structure at N=28 via the
reaction 46Ar(3He,d)47K (spokesperson : A. Gottardo
(INFN-LNL) and M. Assié).