Erlangen 2026 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 4: Structure and Dynamics of Nuclei I

HK 4.6: Talk

Monday, March 16, 2026, 18:00–18:15, AM 00.011

The isovector spin-M1 response of ⁹⁰Zr and ⁹²Mo — •A. Gupta¹, V. Werner¹, A. D. Ayangeakaa^{2, 3}, M. Beuschlein¹, S. W. Finch^3,4, U. F. Gayer^3,4,5, D. Gribble^{2, 3}, J. Hauf¹, K. E. Ide¹, J. Isaak¹, X. James^{2, 3}, R. V. F. Janssens^{2, 3}, S. R. Johnson^{2, 3}, J. Kleemann¹, P. Koseoglou¹, T. Kowalewski^{2, 3}, B. Löher⁶, O. Papst¹, N. Pietralla¹, A. Saracino^{2, 3}, D. Savran⁶, and N. Sensharma^2,3 — ¹IKP, TU Darmstadt — ²UNC, Chapel Hill, NC, USA — ³TUNL, Durham, NC, USA — ⁴Duke U., Durham, NC, USA — ⁵ESS, Lund, SE — ⁶GSI, Darmstadt

Electron-capture rates in medium-heavy nuclei are crucial for deleptonization in late core-collapse supernovae. These rates depend strongly on Gamow-Teller (GT) strength [1], though direct measurements remain difficult. The isovector spin-flip M1 (IVSM1) response, an isospin analogue of GT transitions, provides an alternative probe, which we investigate in the N = 50 isotones ⁹⁰Zr and ⁹²Mo. The two extra protons in ⁹²Mo’s g_9/2 orbital beyond the closed pf shell may enhance its IVSM1 strength relative to ⁹⁰Zr. The dipole response of both nuclei was studied via nuclear resonance fluorescence using a new hybrid HPGe Clover-LaBr₃ array at the HIγS facility. Ground-state transition asymmetries will be used to extract the total M1/E1 strength up to 10 MeV. The experimental details and preliminary results for the total M1 strength distribution will be presented.

Supported by DFG Project No.279384907-SFB 1245 and the U.S. DOE Grant No. DE-FG02-97ER41041 and No. DE-FG02-97ER41033.

[1] K. Langanke et al., Rep. Prog. Phys. 84, 066301 (2021)

Keywords: Isovector spin-M1 strength; core-collapse supernovae; dipole response; nuclear resonance fluorescence