JYFL-ACCLAB-JM27 Collectivity and shape phenomena in extremely neutron deficient A ≈ 120 Lanthanides, Addendum JM03

JM27:

Collectivity and shape phenomena in extremely neutron deficient A ≈ 120 Lanthanides (Addendum JM03)

Spokesperson: C. Petrache, B. Cederwall

Liaisons: A. Briscoe

Collaboration: JYFL - Orsay - KTH

Date: 04.10.2021-11.10.2021
Nucleus: 120La, 119La, 118Cs, 117Cs
Beam (charge state): 64Zn11+
Target (thickness): 58 Ni(1.0 mg/cm2, 0.95 mg/cm2)
Degrader (thickness): 48 ug/cm²
Beam energy: 275, 255 MeV
Beam intensity: 1.5-4 pnA
Beam hours delivered roughly: 168 hours
Instrumentation: JUROGAM 3, MARA, DSSD (BB20 300-um thick), MWPC, focal plane Ge-array: 3 BEGes + 1 clover, 2x punch through Si 1 mm.
MARA Electric Dipole setting: 129-148 kV

Objectives(less than 250 words):

Study collectivity and shape phenomena in extremely neutron deficient A ≈ 120 Lanthanides by aiming to discover excited states in 120La. Additionally, obtain a high-statistic data set on ancillary residual nuclei to reach terminating states of the (h11/2)x(h11/2) valence space.

Achievements (less than 250 words): We performed very successful experiment. Regarding the 120La part, evidence of two cascades first observed in the previous JM03 experiment were observed seperately in at 275 MeV and 255 MeV respectively, leading to the tentative assignment of the latter to 120La; a superior m/q spectrum with respect the first run and La X-rays will aid with firm assignment during offline analysis. The other band of interest, after being observed only at a higher energy, is thought to belong to 117/118Cs.

Comments: MARA performed very well and spectra were notably clean. During the latter days of the experiment the beam intensity was increased until 25 kHz and 45 kHz were observed in the DSSD and MWPC, respectively.