1. |
- Koldste, G. T., et al.
(författare)
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Relative proton and gamma widths of astrophysically important states in S-30 studied in the beta-delayed decay of Ar-31
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 87:5
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Tidskriftsartikel (refereegranskat)abstract
- Resonances just above the proton threshold in S-30 affect the P-29(p, gamma)S-30 reaction under astrophysical conditions. The (p,gamma)-reaction rate is currently determined indirectly and depends on the properties of the relevant resonances. We present here a method for finding the ratio between the proton and gamma partial widths of resonances in S-30. The widths are determined from the beta 2p- and beta p gamma-decay of Ar-31, which is produced at the ISOLDE radioactive ion beam facility at the European research organization CERN. Experimental limits on the ratio between the proton and gamma partial widths for astrophysical relevant levels in S-30 have been found for the first time. A level at 4689.2(24) keV is identified in the gamma spectrum, and an upper limit on the Gamma(p)/ Gamma gamma ratio of 0.26 (95% C.L.) is found. In the two-proton spectrum two levels at 5227(3) keV and 5847(4) keV are identified. These levels were previously seen to gamma decay and upper limits on the Gamma(gamma)/Gamma(p) ratio of 0.5 and 9, respectively, (95% C.L.) are found, where the latter differs from previous calculations.
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2. |
- Tengblad, Olof, 1957, et al.
(författare)
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LaBr3(Ce):LaCl3(Ce) Phoswich with pulse shape analysis for high energy gamma-ray and proton identification
- 2013
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 704:0, s. 19-26
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Tidskriftsartikel (refereegranskat)abstract
- A novel Phoswich design based on new generation scintillator crystals is presented. The detector composed from a combination of a LaBr3(Ce) with a LaCl3(Ce) crystal in one cylinder coupled to a photo multiplier tube has been tested both for incident gamma rays in the range of 0.3–6 MeV, as well as for high energy protons in the range 120–180 MeV. The Phoswich assembly has not significantly deteriorated the energy resolution, which for 662 KeV gamma rays gives a resolution of 4.5%, while for high energy protons (Ep=180 MeV) an energy resolution of 1% was obtained. It is shown that the signals from the two crystals can be separated in an event by event based mode. Using direct digitizing of the detector pulse an off-line pulse-shape analysis was performed built either on a total to tail or total to pulse height method in order to fully identify the incoming radiation. Our aim with this R&D is to in the future build a detector which is able to detect with good efficiency and resolution over a wide energy range; 0.1–30 MeV gamma rays and 20–400 MeV protons. Monte Carlo simulations made in order to design the next prototype are presented.
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