Sullivan, C. ; Zegers, R. G. T. ; Noji, S. ; Austin, Sam M. ; Schmitt, J. ; Aoi, N. ; Bazin, D. ; Carpenter, M. ; Carroll, J. J. ; Fujita, H. ; Garg, U. ; Gey, G. ; Guess, C. J. ; Hoang, T. H. ; Harakeh, M. N. ; Hudson, E. ; Ichige, N. ; Ideguchi, E. ; Inoue, A. ; Isaak, J. ; Iwamoto, C. ; Kacir, C. ; Koike, T. ; Kobayashi, N. ; Lipschutz, S. ; Liu, M. ; Neumann-Cosel, P. von ; Ong, H. J. ; Pereira, J. ; Raju, M. Kumar ; Tamii, A. ; Titus, R. ; Werner, V. ; Yamamoto, Y. ; Fang, Y. D. ; Zamora, J. C. ; Zhu, S. ; Zhou, X. (2018)
The ( Li6,Li*6[3.56MeV] ) reaction at 100 MeV/u as a probe of Gamow-Teller transition strengths in the inelastic scattering channel.
In: Physical Review C, 98 (1)
doi: 10.1103/PhysRevC.98.015804
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Background: Inelastic neutrino-nucleus scattering is important for understanding core-collapse supernovae and the detection of emitted neutrinos from such events in earth-based detectors. Direct measurement of the cross sections is difficult and has only been performed on a few nuclei. It is, therefore, important to develop indirect techniques from which the inelastic neutrino-nucleus scattering cross sections can be determined.

Purpose: This paper presents a development of the (6Li,6Li∗[T=1,Tz=0,0+,3.56MeV]) reaction at 100 MeV/u as a probe for isolating the isovector spin-transfer response in the inelastic channel (ΔS=1,ΔT=1,ΔTz=0) from which the Gamow-Teller transition strengths from nuclei of relevance for inelastic neutrino-nucleus scattering cross sections can be extracted.

Method: By measuring the 6Li ejectile in a magnetic spectrometer and selecting events in which the 3.56 MeV γ ray from the decay of the 6Li∗[3.56MeV] state is detected, the isovector spin-transfer selectivity is obtained. High-purity germanium clover detectors served to detect the γ rays. Doppler reconstruction was used to determine the γ energy in the rest frame of 6Li. From the 6Li and 3.56 MeV γ-momentum vectors the excitation energy of the residual nucleus was determined.

Results: In the study of the 12C(6Li,6Li∗[3.56MeV]) reaction, the isovector spin-transfer excitation-energy spectrum in the inelastic channel was successfully measured. The strong Gamow-Teller state in 12C at 15.1 MeV was observed. Comparisons with the analog 12C(6Li,6He) reaction validate the method of extracting the Gamow-Teller strength. In measurements of the 24Mg,93Nb(6Li,6Li∗[3.56MeV]) reactions, the 3.56 MeV γ peak could not be isolated from the strong background in the γ spectrum from the decay of the isoscalar excitations. It is argued that by using a γ-ray tracking array instead of a clover array, it is feasible to extend the mass range over which the (6Li,6Li∗) reaction can be used for extracting the isovector spin-transfer response up to mass numbers of ∼25 and perhaps higher.

Conclusions: It is demonstrated that the (6Li,6Li∗[3.56MeV]) reaction probe can be used to isolate the inelastic isovector spin-transfer response in nuclei. Application to nuclei with mass numbers of about 25 or more, however, will require a more efficient γ-ray array with a better tracking capability.

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