[en] Short note

[en] Abstract only

[en] Previous Studies of Gamow-Teller Strength in the A=37 region have found poor agreement between sd-shell model estimates and measurements based upon Β⁺-delayed proton emission. One reason may be that this system is so close to the fp shell that multi hw excitations may be necessary in the model space. However, the structure of states in ^31,33Ar should not be as heavily affected by multi hw excitations. These nuclei should, thus, allow a more quantitative comparison between experiment and theory. They also involve a larger Β⁺ Q window. Therefore, in support of planned Β⁺-delayed proton emission experiments on these nuclei, we have calculated the Β⁺ GT strength functions for ^31,33Ar using two different interactions. Comparison between these results (and other calculations in the literature) test the sensitivity of the calculated GT strength functions within the β⁺ Q window to the interaction and model space employed

[en] Masses of the short-lived radionuclides Ar³² (T_1/2=98 ms) and Ar³³ (T_1/2=173 ms) have been determined with the Penning trap mass spectrometer ISOLTRAP. Relative uncertainties of 6.0x10^-8 (δm=1.8 keV) and 1.4x10^-8 (δm=0.44 keV), respectively, have been achieved. At present, these new mass data serve as the most stringent test of the quadratic form of the isobaric-multiplet mass equation. Furthermore, the improved accuracy for the mass of Ar³² will allow for a better constraint on scalar contributions to the weak interaction. New mass values have also been measured for Ar⁴⁴ and Ar⁴⁵, and a 20σ deviation for Ar⁴⁴ from the literature value was found and interpreted

[en] The β decay data of ^32,33Ar, recently revisited at the low energy line of SPIRAL at GANIL, is used to illustrate the structure information we can get from βp precusors when a highly performing setup is used.

No abstract available

[en] Recently, the applicability of Penning trap mass spectrometry has been extended to nuclides with a half-life of less than one second. The mass of ³³Ar (T_1/2=174 ms) was measured using the ISOLTRAP spectrometer with an accuracy of 4.2 keV. This measurement provided a stringent test of the Isobaric Multiplet Mass Equation (IMME) at mass number A=33 and isospin T=3/2. The fast measurement cycle that shows the way to other measurements of very-short-lived nuclides is presented. Furthermore, the results of the IMME test are displayed

[en] It has been recognized for many years that delayed particle decay (alpha, proton or neutron decay after a beta decay) is sensitive to the kinematics of the β decay. Recoil ion energies subsequent to a beta decay are of the order of 100 eV for light isotopes. If this daughter nucleus is unstable to particle decay, the ion recoil will cause a kinematic shift in the particle energy in the lab frame of the order of 10 keV, which is easily detected with current semiconductor particle detectors. This technique has been used to probe the beta-neutrino angular correlation by detecting the alpha-alpha angular correlation in the decay of ⁸Li, by observing increased spectral width of the delayed particles, or by observing a centroid particle energy difference between spectra in coincidence with beta particles at various angles to the particle decay direction. This latter technique has the most applications, and is the one the authors will exploit to investigate the nuclear and weak interaction physics of the beta decay of ³³Ar

[en] A multi-hit capacity setup was used to study the decay of the drip-line nucleus "3"1Ar, produced at the ISOLDE facility at CERN. A spectroscopic analysis of the β-delayed three-proton decay of "3"1Ar is presented for the first time together with a quantitative analysis of the β-delayed 2pγ decay. A new method for determination of the spin of low-lying levels in the βp daughter "3"0S using proton-proton angular correlations is presented and used to determine that the spin of the 5.2-MeV level is most likely 3"+ with 4"+ also possible. The half-life of "3"1Ar is found to be 15.1(3) ms. An improved analysis of the Fermi β strength including the β3p-decay mode gives a total measured branching ratio of 3.60(44)%, which is lower than the theoretical value found to be 4.24(43)%. Finally, a previously unidentified γ transition from the isobaric analog state in the decay of "3"3Ar has been found. (authors)

[en] An improved method for processing digital signals of the Frisch-grid ionization chamber to measure the electron drift velocity is proposed, which is based on the analysis of the cathode signal and the differentiated cathode signal. This method allows the real-time measurement eliminating the influence of electron diffusion and it is suitable for working gases with electron loss from the electronegative impurities. The electron drift velocities in gas mixtures of Ar $+$ 9.86% CH₄, Ar $+$ 3.45% CO₂, (Ar $+$ 3.45% CO₂) $+$ x% O${}_2$ (x is less than 0.33), (Ar $+$ 3.45% CO₂) $+$ y% Air (y is less than 2.09) have been measured, and the results are compared with existing measurements and calculations using MAGBOLTZ-11.4 code. Meanwhile, the influences of the impurities of oxygen and nitrogen on the electron drift velocity are analyzed.