In this review, we discuss the present status of three indirect techniques that are used to determine reaction rates for stellar burning processes, asymptotic normalization coefficients, the Trojan ...Horse method and Coulomb dissociation. A comprehensive review of the theory behind each of these techniques is presented. This is followed by an overview of the experiments that have been carried out using these indirect approaches.
A MICROMEGAS detection amplifier has been incorporated into the design of the TAMU-MDM focal plane detector with the purpose of improving the energy resolution and thus, the particle identification. ...Beam tests showed a factor of 2 improvement over the original design, from 10%–12% to 4%–6%, for ions with A≤40 at E/A ∼ 10–20 MeV.
A gridded ionization chamber used as a focal plane detector at the back of the TAMU-MDM spectrometer was modified to use MicroMegas technology for the purpose of improving energy resolution and ...particle identification. The upgraded system was tested in experimental conditions with several heavy-ion beams at 12MeV/u and found to achieve resolutions between 3.2% and 4.8%. This is a significant improvement over the previous performance of 10–15% obtained using the existing, conventional ionization chambers.
AstroBox2 – Detector for low-energy β-delayed particle detection Saastamoinen, A.; Pollacco, E.; Roeder, B.T. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
06/2016, Letnik:
376, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Efficient suppression of β-background is essential for studies of low-energy β-delayed charged particle decays of astrophysical interest. A promising method for such studies has been a micro pattern ...gas amplifier detector where the sample is implanted into the gas volume and the decays that follow are observed with high gain and signal to noise ratio. An upgraded version of the original AstroBox detector has been built and commissioned at Texas A&M University. Here a description of the new AstroBox2 detector is given, selected results from the commissioning tests are presented, and future perspectives discussed.
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.
Nonmonotonic variation with collision energy (sqrts_{NN}) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of ...the system, is suggested as a signature for the quantum chromodynamics critical point. We report the first evidence of a nonmonotonic variation in the kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of sqrts_{NN} with 3.1 σ significance for head-on (central) gold-on-gold (Au+Au) collisions measured solenoidal tracker at Relativistic Heavy Ion Collider. Data in noncentral Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of sqrts_{NN}.
A precision measurement of the γ yields following the β decay of (32)Cl has determined its isobaric-analogue branch to be (22.47(-0.18)(+0.21))%. Since it is an almost pure-Fermi decay, we can also ...determine the amount of isospin-symmetry breaking in this superallowed transition. We find a very large value, δ(C) = 5.3(9)%, in agreement with a shell-model calculation. This result sets a benchmark for isospin-symmetry-breaking calculations and lends support for similarly calculated, yet smaller, corrections that are currently applied to 0+ → 0 + transitions for tests of the standard model.
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