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1. Spectroscopic study of the 4f 7 6s 2 8 S 7/2∘ – 4f 7 ( 8 S ° ) 6s6p( 1 P ° ) 8 P 5/2,7/2 transitions in neutral europium-151 and europium-153: absolute frequency and hyperfine structure

   https://doi.org/10.1364/JOSAB.521181  

   Maruko, C. ; Çölmek, N_N ; Herd, M_T ; Ahrendsen, K_J ; Cabrales, B. ; Cannon, G. ; Davis, E. ; Guo, X_Y ; Karani, T. ; Wallace, A. ; et al ( April 2024 , Journal of the Optical Society of America B)

   We report on spectroscopic measurements on the 4f⁷6s²⁸S_7/2^∘−4f⁷(⁸S^∘)6s6p(¹P^∘)⁸P_5/2,7/2transitions at 466.32 nm and 462.85 nm, respectively, in neutral europium-151 and europium-153. The center of gravity frequencies for the 151 and 153 isotopes for both transitions are reported for the first time using saturated absorption spectroscopy. For the 6s6p(¹P^∘)⁸P_5/2state, the center of gravity frequencies were found to be 642,894,493.3(4) MHz and 642,891,693.3(9) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to beA(151)=−157.01(3)MHz,B(151)=74.5(4)MHz andA(153)=−69.43(14)MHz,B(153)=191.0(26)MHz. These hyperfine values are all consistent with previously published results except forB(151) that has a small discrepancy. The isotope shift was found to be 2799.54(20) MHz, a small discrepancy with previously published results. For the 6s6p(¹P^∘)⁸P_7/2state, the center of gravity frequencies were found to be 647,708,930.6(6) MHz and 647,705,958.4(26) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to beA(151)=−218.66(4)MHz,B(151)=−293.4(8)MHz andA(153)=−97.15(13)MHz,B(153)=−750(3)MHz. These values are all consistent with previously published results except forA(151) that has a small discrepancy. The isotope shift was found to be 2972.8(5) MHz, a small discrepancy with previously measured results.

    

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2. 58 Ni( 3 He,t) 58 Cu*(γ) measurements with GODDESS to constrain the astrophysical rate of 57 Ni(p,γ) 58 Cu

   https://doi.org/10.1088/1742-6596/2586/1/012109  

   Carmichael, S R ; Pain, S D ; Siciliano, M ; Allen, J ; Bardayan, D W ; Boomershine, C ; Campbell, C M ; Carpenter, M P ; Chipps, K A ; Cizewski, J A ; et al ( September 2023 , Journal of Physics: Conference Series)

   The observation ofγrays from the decay of⁴⁴Ti in the remnants of core-collapse supernovae (CCSNe) provides crucial information regarding the nucleosynthesis occurring in these events, as⁴⁴Ti production is sensitive to CCSNe conditions. The final abundance of⁴⁴Ti is also sensitive to specific nuclear input parameters, one of which is the⁵⁷Ni(p,γ)⁵⁸Cu reaction rate. A precise rate for⁵⁷Ni(p,γ)⁵⁸Cu is thus critical if⁴⁴Ti production is to be an effective probe into CCSNe. To experimentally constrain the⁵⁷Ni(p,γ)⁵⁸Cu rate, the structure properties of⁵⁸Cu were measured via the⁵⁸Ni(³He,t)⁵⁸Cu*(γ) reaction using GODDESS (GRETINA ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory’s ATLAS facility. Details of the experiment, ongoing analysis, and plans are presented.

    

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3. Study of the 44 Ti(α, p) 47 V reaction rate using high-precision 50 Cr(p, t) 48 Cr measurements

   https://doi.org/10.1088/1742-6596/2586/1/012106  

   Binda, S D ; Adsley, P ; Long, A M ; Berg, G ; Brümmer, J W ; Couder, M ; Görres, J ; Kamimota, M ; Khumalo, N ; Köhne, M ; et al ( September 2023 , Journal of Physics: Conference Series)

   The abundance and distribution of⁴⁴Ti tells us about the nature of the core-collapse supernovae explosions. There is a need to understand the nuclear reaction network creating and destroying⁴⁴Ti in order to use it as a probe for the explosive mechanism. The⁴⁴Ti(α, p)⁴⁷V reaction is a very important reaction and it controls the destruction of⁴⁴Ti. Difficulties with direct measurements have led to an attempt to study this reaction indirectly. Here, the first step of the indirect study which is the identification of levels of the compound nucleus⁴⁸Cr is presented. A 100-MeV proton beam was incident on a⁵⁰Cr target. States in⁴⁸Cr were populated in the⁵⁰Cr(p, t)⁴⁸Cr reaction. The tritons were momentum-analysed in the K600 Q2D magnetic spectrometer at iThemba LABS.

    

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4. Fine-structure Transitions of Ne + , Ar + , Ne 2+ , and Ar 2+ Induced by Collisions with Atomic Hydrogen

   https://doi.org/10.3847/1538-4357/ad0e77  

   Yan, Pei-Gen ; Babb, James F ( January 2024 , The Astrophysical Journal)

   We calculate cross sections for fine-structure transitions of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with atomic hydrogen by using quantum-mechanical methods. Relaxation rate coefficients are calculated for temperatures up to 10,000 K. The temperature-dependent critical densities for the relaxation of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with H have been determined and compared to the critical densities for collisions with electrons. The present calculations will be useful for studies utilizing the infrared lines [Neii] 12.8, [Neiii] 15.6, [Neiii] 36.0, [Arii] 6.99, [Ariii] 8.99, and [Ariii] 21.8μm as diagnostics of, for example, planetary nebulae and star formation.

    

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5. The 41 Ar(n,y) 42 Ar reaction

   https://doi.org/10.1051/epjconf/202328401037  

   Sahoo, R. N. ; Paul, M. ; Köster, U. ; Scott, R. ; Tessler, M. ; Zylstra, A. ; Avila, M. L. ; Dickerson, C. ; Jayatissa, H. ; Kohen, M.S. ; et al ( January 2023 , EPJ Web of Conferences)

   Mattoon, C.M. ; Vogt, R. ; Escher, J. ; Thompson, I. (Ed.)

   The cross-section of the thermal neutron capture⁴¹Ar(n,γ)⁴²Ar(t_1/2=32.9 y) reaction was measured by irradiating a⁴⁰Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived⁴²K(12.4 h) β⁻daughter of⁴²Ar. Our preliminary value of the⁴¹Ar(n,γ)⁴²Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of⁴²Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA.

    

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