M22: Completing the proton drip line with promethium Spokesperson: A. D. Briscoe, J. Uusitalo Liaisons: A. Briscoe Collaboration: JYFL, University of Liverpool , Orsay, GSI Date: 28.03.2022-04.04.2022 Nucleus: 126Pm, 127Pm, Beam (charge state): 78Kr11+ Target (thickness): 54Fe (1.2 mg/cm2) 92Mo ( 550 ug/cm2) Degrader (thickness): 400 ug/cm² (thick to degrade recoil energy due to deflector issue) Beam energy: 422, 435, 380 MeV Beam intensity: 0.5-1.5 pnA, 5 pnA Beam hours delivered roughly: 150 hours Instrumentation: , MARA, DSSD (BB20 150um thick) (traces enabled x - side), MWPC, focal plane Ge-array: 3 BEGes + 1 clover, 2x punch through Si 1 mm., JYtube, JUROGAM 3.14( Phase 1s) MARA Electric Dipole setting: asymmetric voltages anode 155 kV Cathode 160-210 kV Objectives(less than 250 words): Search for ground state direct proton decays of 126Pm and 127Pm. At the PACs recommendation and deflector constraints it was decided to not try 125Pm at the current time, so we spent 1 week on 126,127Pm. Achievements (less than 250 words): The experiment ran very smoothly, MARA seemed to perform very well with the asymmetric reaction. Using a thick carbon foil to degrade did not cause any issue with detectors at target position, also good mass resolving power was maintained. Unfortunately during the online phase of the experiment, there was no clear sign of the proton decay of 126Pm nor 127Pm. Traces were collected throughout and a careful offline analysis is needed in order to draw conclusions and at least set limits on the possible qvalues per available nillson orbital, work is ongoing. On the other hand, even without the observation of proton emission, numerous gamma-decaying isomers were observed, some for the first time and others can be incorporated in ongoing MARA isomers study from M9 and JM06: 127Pm, 125La, 126La, 125Ba, 120Ba, + 2 x yet unidentified (Jurogam + Fp cascades), 165W.

2025