[en] Dimethyl sulfoxide (DMSO) is electrochemically co-intercalated with lithium ions into graphite to form a stable ternary graphite-intercalation-compound (GIC), Li-DMSO-GIC. To elucidate the details of the co-intercalation behavior, in situ Raman spectroscopy was performed to observe the structural variations in graphite during the potential scan. During the scan from 2.44 to 1.00 V, DMSO was co-intercalated with lithium ions into graphite, exhibiting a staged structure. The stage number decreased from 4 to 1. During the scan from 1.00 to 2.44 V, the deintercalation of DMSO-solvated lithium ions was observed. After experienced a potential cycle between 2.4 and 0 V, the graphite exhibited significant changes that are ascribed to the exfoliation of graphite, implying that the destruction of the graphite composite electrode is likely to be caused by the decomposition of DMSO within the graphite layer.

[en] We discuss the motivation and technique of Penning trap mass spectrometry applied to radioactive ⁴⁴V and ^44mV, using the LEBIT 9.4 T Penning trap mass spectrometer at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. A complementary measurement of these nuclides, performed at the CSRe in Lanzhou, China, was recently published, but with errors several times larger than obtainable for a short-lived radionuclide in a Penning trap. Interpretation of the higher precision results is ongoing and a full accounting of this measurement is anticipated in the coming months.

[en] We have calculated the β⁺ decay of the proton-rich nuclei ⁴⁴V in the full fp-shell valence space. Using the standard quenching factor 0.77 for the Gamow-Teller (GT) operator we obtain a theoretical half-life of 71 ms in good agreement with the experimental value t_1/2=90±25 ms. We also compute the Gamow-Teller strength functions corresponding to the decays of the 2⁺ ground state and 6⁺ isomer state. Our results indicate that 80% of the total GT strength falls within the β⁺ energy window

[en] Weak beta-delayed particle branches are all that is currently known about the decays of ⁴⁴V and ⁵²Co. The as-yet-unobserved superallowed beta-decay branches, as well as allowed Gamow-Teller transitions to low-lying daughter states, should lead instead to beta-delayed γ rays. We have produced ⁴⁴V and ⁵²Co by bombarding a stack of calcium targets with ⁶Li and ¹⁴N beams, respectively, from the TASCC facility. The reaction products were transported with a helfurn-jet transfer system and deposited on the tape of a fast tape-transport system and moved to a counting location where the decays were recorded with plastic scintillators (Β) and HPGe (γ) detectors. At least six strong γ rays have been observed from the decay of ⁴⁴V and four from ⁵²Co. In both cases the decays proceed through a 6⁺-4⁺-2⁺-0⁺ cascade in the daughter nuclei. The present status of these experiments and the decay schemes of ⁴⁴V and ⁵²Co will be presented

[en] The present paper reports on the spin-parities and the magnetic moments for the ground states of 44 proton-rich isotopes with Z = 21–30 and A = 36–57, which are important for studies of either reaction rates in X-ray bursts or nuclear structure. These nuclear properties were calculated based on the single-particle shell model. The spins of the concerned nuclei were compared to available experimental data adopted from the NuDat database to evaluate the variations in the astrophysical rates of the rp-process reactions. We found discrepancies, due to the deformed nuclear structure, between the present results and those reported in the NuDat database. The spin uncertainties result in large variations, 13%–200%, in the astrophysical rates of the rp-process reactions. In particular, the spin uncertainties of the ⁴⁴V and the ^46–49Mn isotopes significantly affect the astrophysical rates of the reverse reactions of the proton captures ⁴³Ti(p, γ)⁴⁴V(p, γ)⁴⁵Cr, ⁴⁵Cr(p, γ)⁴⁶Mn(p, γ)⁴⁷Fe, 47Mn(p, γ)⁴⁸ Fe, ⁴⁷Cr(p, γ)48 Mn(p, γ)⁴⁹ Fe, and ⁴⁸Cr(p, γ)⁴⁹ Mn(p, γ)⁵⁰ Fe. Moreover, the magnetic moments of most of the isotopes were predicted for the first time. The results show that the magnetic moments are in the order of μ_p(1f_7/2) > μ_p(2p_3/2) > μ_n(1d3/2) > μ_p (1f_7/2)for thenuclei having an unpaired nucleon in the proton/neutron shells. The present study suggests that reliable calculations and/or measurements for the properties of proton-rich nuclei are highly demanded.

[en] Short communication

[en] The spectral fluctuations and the statistics of electromagnetic transition intensities and electromagnetic moments in ⁴⁴V nucleus are studied by the framework of the interacting shell model, using the FPD6 as a realistic effective interaction in the isospin formalism for 4 particles move in the fp-model space with a ⁴⁰Ca core. To look for a regular-chaos transition in ⁴⁴V nucleus, we perform shell model calculations using various interaction strengths β to the off-diagonal matrix elements of the FPD6. The nearest-neighbors level spacing distribution P(s) and the distribution of electromagnetic transition intensities [such as, B(M1) and B(E2) transitions] are found to have a regular dynamic at β=0, a chaotic dynamic at β⩾0.3 and an intermediate situation at 0<β<0.3. For the Δ₃ statistic we have found a regular dynamic at β=0, a chaotic dynamic at β⩾0.4 and an intermediate situation at 0<β<0.4. It is also found that the statistics of the squares of M1 and E2 moments, which are consistent with a Porter-Thomas distribution, have no dependence on the interaction strength β.

[en] Mass excess values for ⁴⁴V, ⁵²Co and ⁵⁶Cu are derived indirectly using the mirror symmetry and known data from beta-delayed proton spectroscopy. The new mass excess obtained by using the energy conservation for ⁴⁸Mn is $-29303(14)\text{keV}$, which is an improvement by about an order of magnitude compared to the AME'12 value. Compared to previously known data, the new proton separation energy for ⁴⁵Cr causes a ∼3.5 times smaller matter flow through the CaSc cycle during the rp-process. Obtained proton separation energies for ⁵²Co and ⁵⁶Cu are about 500 keV larger than the AME'12 values. If confirmed, this would affect photo disintegration rates of ⁵²Co $(\gamma ,p)$ ⁵¹Fe and ⁵⁶Cu $(\gamma ,p)$ ⁵⁵Ni reactions during the rp-process in X-ray bursts.

[en] We present direct mass measurements of the short-lived ⁴⁴V, ⁴⁸Mn, ⁴¹Ti and ⁴⁵Cr nuclei. A novel experimental method has been used that is based on projectile fragmentation, in-flight separation of relativistic heavy ions with the fragment separator (FRS), and on isochronous operation of the experimental storage ring (ESR). A mass resolving power of 110 000 (FWHM) and an accuracy of about (100-500) keV has been achieved. The impact of the present results on the rp-process in X-ray burst models is discussed

[en] The Silicon Photomultiplier (SiPM) is a compact detector which shows great promise for use in MR compatible PET systems. SiPMs are insensitive to magnetic fields, have a high intrinsic gain (about 10⁶) and operate at low voltages (40 V), eliminating the need for sophisticated shielding and low noise preamplifiers. A prototype 1x1 mm² detector currently under investigation at the University of Toronto consists of an array of 556 independent microcells operating in Geiger mode. Each microcell thus produces a pulse of constant amplitude with the detection of one or more electrons. All microcells are connected in parallel through integrated quenching resistors, and thus the output of the SiPM is the sum of the individual standardized signals and is proportional to energy provided the number of detected light photons is less than the number of microcells. The detector was operated without a preamplifier, and using a 2x2x6 mm² LSO crystal and ²²Na source, the energy resolution was measured to be 25.6±0.4% FWHM and timing resolution for a detector pair was 1.9±0.1 ns FWHM. LED measurements and measurements using ¹³³Ba (356 keV) and ¹³⁷Cs (662 keV) verify that the detector is operating linearly at 511 keV. The major noise contribution is the dark current, which at -44 V results in a peak dark count rate of about 16 kHz that reduces to negligible levels above a 90 keV lower energy threshold. In the next generation of compact multi-element SiPM detectors with improved optical coupling the energy resolution should improve to below 15% FWHM, making them well suited for use in a high performance MR compatible depth of interaction PET scanner