Speaker
Description
The High-Intensity Heavy-Ion Accelerator Facility (HIAF), developed by the Institute of Modern Physics (IMP), is scheduled to operate by the end of 2025. HIAF comprises a superconducting linac, a booster ring, a spectrometer ring, and a High-rigidity Radioactive Ion Beam Line (HIRIBL) connecting these two rings [1]. HIRIBL is an in-flight projectile fragment separator designed to produce purified radioactive ion beams (RIBs) through a two-stage separation process: a pre-separator and a main separator [2]. The upstream accelerator complex provides HIRIBL with a $^{238}\text{U}^{35+}$ beam at an energy of 833 MeV/u with an intensity of $1×10^{11}$ particles per pulse (PPP).
This facility makes it possible to produce spin-controlled RIBs by a two-step projectile fragmentation (PF) mechanism [3], providing unique opportunities for g-factors measurement. Measurements of g factors can help to assign or confirm the spin and parity of a nuclear state, especially in far-from-stability regions, where such assignments are often based on systematics and theoretical predictions.
Since it is the first time to perform such an experiment at the new facility, a simulation work is demanded and important to evaluate the feasibility of producing polarized RIBs at HIRIBL. To do the simulation, LISE++ and MOCADI are employed. A $^{238}\text{U}^{35+}$ primary beam is designed to impinge on a Carbon target. The pre-separator of HIRIBL is used to separate the fission products and select $^{132}\text{Sn}$, which subsequently undergoes projectile fragmentation on a wedge-shaped Aluminum target to produce spin-aligned $^{130}\text{Sn}$. LISE++ is used to calculate the transmission and yields of fragments produced and collected, including the optimization of the primary target thickness, degrader thickness, and slit width [4]. Additionally, it provides rapid estimations of the transmission efficiency and yield of various isotopes based on first-order beam optics transfer matrices. The MOCADI program is also employed to perform transport calculations of RIBs, incorporating third-order transfer matrices generated by the GICOSY program. This allows for detailed tracking of beam particle properties at any point within the optical system and provides a more realistic representation of particle beam dynamics compared to LISE++ [5].
The simulation results show that the obtained $^{130}\text{Sn}$ yield achieves the expected goals, confirming the feasibility of producing spin-controlled RIBs at HIRIBL and providing valuable guidance for experimental design.
Reference
[1] X. H. Zhou, J. C. Yang, and HIAF Project Team, Status of the high-intensity heavy-ion accelerator facility in China, AAPPS Bull. 32, 35 (2022).
[2] L. N. Sheng, X. H. Zhang, H. Ren, et al., Ion-optical updates and performance analysis of High energy FRagment Separator (HFRS) at HIAF, Nucl. Instrum. Meths. Phys. Res. B 547, 165214 (2022).
[3] Y. Ichikawa, H. Ueno, Y. Ishii, et al., Production of spin-controlled rare isotope beams, Nat. Phys. 8, 918 (2012).
[4] O. B. Tarasov, and D. Bazin, LISE++: Radioactive beam production with in-flight separators, Nucl. Instrum. Meths. Phys. Res. B 266, 4657 (2008).
[5] N. Iwasa, H. Weick, and H. Geissel, New features of the Monte-Carlo code MOCADI, Nucl. Instrum. Meths. Phys. Res. B 269, 752 (2011).
| Email address | zhangguoli@impcas.ac.cn |
|---|---|
| Supervisor's Name | Zhiyu Sun |
| Supervisor's email | sunzhy@impcas.ac.cn |
| Funding Agency | Institute of Modern Physics, Chinese Academy of Sciences |
| Classification | Techniques related to high-power radioactive ion beam production |
