Excited states up to 3 MeV in the odd-odd 54Mn have been populated in the 54Cr(p,n)54Mn reaction at Ep = 4.5 MeV. Conversion coefficients (αK and απ) were deduced using the NPG method for the first ...time in 54Mn. Multipolarities were unambiguously assigned in 16 transitions for the first time using the obtained conversion coefficient values. Spin and parity has been restricted for three transitions.
With its unique combination of excellent timing properties and good energy resolution, LaBr3:Ce detectors have proven to be effective tool in gamma spectroscopy and in particular fast-timing studies. ...Eight 2” x 2” LaBr3:Ce detectors used in conjunction with the 16 channel all-digital waveform 500 MHz acquisition module, PIXIE-16 were commissioned at iThemba Laboratory for Accelerator Based Sciences, South Africa. The results presented here give insight of the performance of the 2” x 2” LaBr3 detectors when used in conjunction with a digital pulse processing (DPP) module and electronic read-out module. Initial commissioning experiments were done using radioactive sources, including 60Co, 152Eu and 67Ga. The detectors were then exposed to an in-beam environment using the AFRODITE array with targets 45Sc and 64Ni, with a proton beam energy of 27 MeV.
Abstract
The
50
Cr(p,
γ
)
51
Mn proton capture reaction has been used to study the photon strength functions by utilizing primary gamma ray transitions from the entry states to discrete states of ...known spins and parities. The reaction was conducted with the 3 MV Tandetron accelerator at iThemba LABS which delivered proton beams of 2.5 to 2.740, 2.760 to 3.0 MeV and 3.675 to 4.498 MeV in intervals of 20-25 keV with beam currents of up to 5
μ
A. In this work the proton capture reaction was employed together with the Average Resonance Capture method to extract the shape of the PSF of
51
Mn.
The study of electric monopole (E0) transitions between two 0+ states is important because the monopole strength carries vital information about the nuclear structure due to its direct link with the ...mean squared charge radius r2 and quadrupole deformation parameter β. Therefore, the measurement of internal conversion electrons (ICE) or internal pair formation (IPF) is crucial for E0 transition studies. Transitions between 0+ states do not change angular momentum. Hence, single-photon emission is forbidden, but can decay by conversion electrons or pair formation and two-photon emission which is mostly negligible. In order to implement E0 studies at iThemba LABS, an electron spectrometer that uses a solenoidal magnetic field acting as a lens and a Si(Li) detector has been refurbished and characterized using calibration sources of ICE. Figures of merit have been extracted and compared with simulations. The spectrometer coupled with an array of LaBr3:Ce detectors and Low Energy Photon Spectrometers (LEPS) was successfully implemented for in-beam experiments. Measurements of internal conversion coefficients (ICC) and monopole strengths extracted from in-beam measurements of 72As, 72Ge, and 72Se are presented.
Electric monopole (E0) transitions are a highly sensitive probe of the charge distribution of an atomic nucleus. A large E0 transition strength (ρ2(E0)) is a clear indicator of nuclear shape ...coexistence. In the region between doubly magic 40Ca and 56Ni, E0 transitions have never been observed in the Ti or Cr isotopes, nor in the heavier iron isotopes (56,58Fe). We have performed the first measurements of the E0 transitions in 52Cr via conversion-electron and pair-conversion spectroscopy using the Super-e spectrometer at the Australian National University Heavy Ion Accelerator Facility. We present the first spectra obtained for 52Cr, including the first observation of the E0 transition from the first-excited 0+ state in 52Cr, in both electron-positron pairs and conversion-electron spectroscopy. The preliminary values for the E0 strength in the 1531keV 2+ → 2+ transition in 52Cr is ρ2(E0) × 103 = 470(190), and for the 1728-keV 23+ → 21+ transition, it is ρ2(E0) 103 = 1800(1200). The large E0 strengths observed are consistent with shape coexistence in this region. However, despite the relatively precise observation of the conversion-electron and electron-positron pair intensities, the E0 strengths have large uncertainties. More precise determinations of relevant spectroscopic quantities, such as the state lifetimes and transition mixing ratios for mixed M1 + E2 transitions, are needed to determine the E0 strength more precisely.
Electric monopole (
E
0) transitions are a highly sensitive probe of the charge distribution of an atomic nucleus. A large
E
0 transition strength (
ρ
2
(
E
0)) is a clear indicator of nuclear shape ...coexistence. In the region between doubly magic
40
Ca and
56
Ni,
E
0 transitions have never been observed in the Ti or Cr isotopes, nor in the heavier iron isotopes (
56,58
Fe). We have performed the first measurements of the
E
0 transitions in
52
Cr via conversion-electron and pair-conversion spectroscopy using the Super-e spectrometer at the Australian National University Heavy Ion Accelerator Facility. We present the first spectra obtained for
52
Cr, including the first observation of the
E
0 transition from the first-excited 0
+
state in
52
Cr, in both electron-positron pairs and conversion-electron spectroscopy. The preliminary values for the
E
0 strength in the 1531keV
2
+
→
2
+
transition in
52
Cr is
ρ
2
(
E
0) × 10
3
= 470(190), and for the 1728-keV 2
3
+
→ 2
1
+
transition, it is
ρ
2
(
E
0) 10
3
= 1800(1200). The large
E
0 strengths observed are consistent with shape coexistence in this region. However, despite the relatively precise observation of the conversion-electron and electron-positron pair intensities, the
E
0 strengths have large uncertainties. More precise determinations of relevant spectroscopic quantities, such as the state lifetimes and transition mixing ratios for mixed
M
1 +
E
2 transitions, are needed to determine the
E
0 strength more precisely.
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