Development of a position-sensitive large-area microchannel plate (MCP) detector based detection system is reported. Two MCPs with 120 mm active diameter, mounted in chevron configuration, with ...delay-line anode are read out by a digital data-acquisition system consists of fast-timing amplifier unit and CAEN v1751 waveform digitizer. Details of the digital pulse processing, programmed triggering and calibration setup are described. The obtained position resolution was studied using α-particles, the best resolutions on X and Y axes are 460 ± 1μm and 579 ± 1μm in FWHM, respectively.
The nuclear structure of 66 Se, nucleus beyond the N=Z line on the proton-rich side of the valley of stability, was investigated by the neutron knock-out reaction 67 Se( 12 C,X) 66 Se using a 12 C ...target. The analysis of the singles spectrum of the γ-rays emitted during the de-excitation of the populated low-lying excited states revealed two previously detected (927(4) keV, 1460(32) keV) and three new (744(6) keV, 1210(17) keV, 1661(23) keV) transitions. The 744-keV, the 1210-keV, and the 1460-keV transitions were found to be in coincidence with the one at 927 keV. The spectrum coincident with the 927-keV transition showed a further possible transition at 299(35) keV, which was obscured by significant atomic background in the singles spectrum. This transition might correspond to a peak previously reported at 273(5) keV that could not be assigned to 66 Se unambiguously. Based on a comparison of the experimental data to theoretical calculations, four new excited states are proposed which suggest that 66 Se exhibits shape coexistence.
The literature half-life value of 65Ga is based on only one experiment carried out more than 60 years ago and it has a relatively large uncertainty. In the present work this half-life is determined ...based on the counting of the γ-rays following the β-decay of 65Ga. Our new recommended half-life is t1/2 = (15.133 ± 0.028) min which is in agreement with the literature value but almost one order of magnitude more precise.
•Based on gamma-spectroscopy the half-life of 65Ga is measured.•Systematic uncertainties are carefully studied.•The obtained result is (15.133 +- 0.028)min.•This results is in agreement with the only available value in literature, but almost one order of magnitude more precise.
The observation of neutrinos emitted in the p − p chain and in the CNO cycle can be employed to test the Standard Solar Model. The 3He(α,γ)7Be reaction is the first reaction of the 2nd and 3rd branch ...of the p − p chain, so the indetermination of its cross section significantly affects the predicted 7Be and 8B neutrino fluxes. Notwithstanding its relevance and the great deal of experimental and theoretical papers, information of the reaction cross section at energies of the core of the Sun (15 keV - 30 keV) is sparse and additional experimental work is necessary to attain the target (~ 3%) accuracy. The precise understanding of the external capture component to the 3He(α,γ)7Be reaction cross section is pivotal for the theoretical assessment of the reaction mechanism. In this work, the indirect measurement of this external capture component using the Asymptotic Normalization Coefficient (ANC) technique is discussed. To extract the ANC, the angular distributions of deuterons yielded in the 6Li(3He,d)7Be α-transfer reaction were detected with high precision at E3He=3.0 MeV and 5.0 MeV. The ANCs were then deduced from the juxtaposition of DWBA and CC calculations with the experimental angular distributions and the zero energy astrophysical S-factor for 3He(α,γ)7Be reaction was calculated to equal 0.534 ± 0.025 keVb. Both our experimental and theoretical approaches were tested through the analysis of the 6Li(p,γ)7Be astrophysical factor, with further interesting astrophysical implications.
The Gamow-Teller strength distribution of the decay of 186Hg into 186Au has been determined for the first time using the total absorption gamma spectroscopy technique and has been compared with ...theoretical QRPA calculations using the SLy4 Skyrme force. The measured Gamow-Teller strength distribution and the half-life are described by mixing oblate and prolate configurations independently in the parent and daughter nuclei. In this theoretical framework the best description of the experimental beta strength is obtained with dominantly prolate components for both parent 186Hg and daughter 186Au. The approach also allowed us to determine an upper limit of the oblate component in the parent state. The complexity of the analysis required the development of a new approach in the analysis of the X-ray gated total absorption spectrum.
•The Gamow-Teller strength distribution of the decay of 186Hg into 186Au has been determined for the first time using the total absorption gamma spectroscopy technique and has been compared with theoretical QRPA calculations using the SLy4 Skyrme force.•The measured Gamow-Teller strength distribution and the half-life are described by mixing oblate and prolate configurations independently in the parent and daughter nuclei. In this theoretical framework the best description of the experimental beta strength is obtained with dominantly prolate components for both parent 186Hg and daughter 186Au.•The approach also allowed us to determine an upper limit of the oblate component in the parent state, which also describes nicely the experimental beta strength and provides the best description of the half-life of the decay within this framework.•The complexity of the analysis required the development of a new approach in the analysis of the X-ray gated total absorption spectrum. This approach can also be of particular interest for cases where the β+ component of the β-decay can contaminate the X-ray gated spectra.
The nuclear structure of 66Se, nucleus beyond the N=Z line on the proton-rich side of the valley of stability, was investigated by the neutron knock-out reaction 67Se(12C,X)66Se using a 12C target. ...The analysis of the singles spectrum of the γ-rays emitted during the de-excitation of the populated low-lying excited states revealed two previously detected (927(4) keV, 1460(32) keV) and three new (744(6) keV, 1210(17) keV, 1661(23) keV) transitions. The 744-keV, the 1210-keV, and the 1460-keV transitions were found to be in coincidence with the one at 927 keV. The spectrum coincident with the 927-keV transition showed a further possible transition at 299(35) keV, which was obscured by significant atomic background in the singles spectrum. This transition might correspond to a peak previously reported at 273(5) keV that could not be assigned to 66Se unambiguously. Based on a comparison of the experimental data to theoretical calculations, four new excited states are proposed which suggest that 66Se exhibits shape coexistence.
A project has been launched for the development of a laser-based neutron source with the few-cycle lasers available at ELI ALPS. Here we show the first experiments, when deuterons were accelerated ...from ultrathin deuterated foils at 1 Hz repetition rate with the use of 12 fs, 21 mJ laser pulses. The energy spectra of the accelerated deuterons were measured with Thomson ion spectrometers both in forward and backward directions. The accelerated deuterons induced
2
H +
2
H fusion reaction in a deuterated polyethylene disk. The resulting fast neutrons were measured with a time-of-flight (ToF) detector system, within which each detector consisted of a plastic scintillator and a photomultiplier, at four different angles relative to the normal of the neutron converter disk. We found good agreement with the simulated angular distribution and energy spectra. Here, we also present preparations for the next phases when the repetition rate is increased to 10 Hz. The developed flat liquid jet was demonstrated to accelerate protons over 0.6 MeV cutoff energy with a stability better than 4% for 15 min. We developed two further neutron measurement techniques: a liquid scintillator, the ToF signal of which was evaluated with the pulse shape discrimination method, and a bubble detector spectrometer calibrated against a conventional PuBe source. One of the first upcoming applications is the irradiation of zebrafish embryos with laser-generated ultrashort bunch neutrons. As this experiment needs to be implemented in vacuum, the steps of careful preparation and calibration measurements are also discussed.
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