We report on the first γ-ray spectroscopy of 51,53K produced via the 52,54Ca(p,2p) reactions at ∼250 MeV/nucleon. Unambiguous final-state angular-momentum assignments were achieved for beam ...intensities down to few particles per second by using a new technique based on reaction vertex tracking combined with a thick liquid-hydrogen target. Through γ-ray spectroscopy and exclusive parallel momentum distribution analysis, 3/2+ ground states and 1/2+ first excited states in 51,53K were established quantifying the natural ordering of the 1d3/2 and 2s1/2 proton-hole states that are restored at N = 32 and 34. State-of-the-art ab initio calculations and shell-model calculations with improved phenomenological effective interactions reproduce the present data and predict consistently the increase of the E(1/21+) - E(3/21+) energy differences towards N = 40.
Searches for new physics push experiments to look for increasingly rare interactions. As a result, detectors require increasing sensitivity and specificity, and materials must be screened for ...naturally occurring, background-producing radioactivity. Furthermore, the detectors used for screening must approach the sensitivities of the physics-search detectors themselves, thus motivating iterative development of detectors capable of both physics searches and background screening. We report on the design, installation, and performance of a novel, low-background, fourteen-element high-purity germanium detector named the CAGe (CUP Array of Germanium), installed at the Yangyang underground laboratory in Korea.
The α-clusterization of an atomic nucleus has been studied for a long time, even from the earliest days of nuclear physics. Our understanding of the α-cluster structure is, however, mainly limited to ...the self-conjugate
A
= 4
n
(
n
= 2, 3, 4, · · · ) light nuclei and some of the neutron-rich radionuclides such as
10
Be,
11
B, and
14
C. In order to study the α-cluster structure of a neutron-deficient
22
Mg nucleus, we have measured the
18
Ne(α, α)
18
Ne scattering in inverse kinematics by using radioactive
18
Ne beams and the
4
He gas target at the Center for Nuclear Study radioactive ion beam separator of the University of Tokyo. Recoiling α particles from the scattering were detected by using silicon strip detectors, which constitute Δ
E
-
E
telescopes for particle identification. By adopting a thick target method, we were able to investigate a wide range of excitation energies
E
x
= 9.9 - 16.5 MeV in
22
Mg in this work.
New fast-timing γ-ray detection system in Korea: KHALA Moon, B.; Lee, J.; Jang, Y. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
August 2023, 2023-08-00, Letnik:
541
Journal Article
Recenzirano
KHALA, the acronym for Korea high-resolution array of LaBr3(Ce), has been developed to measure the lifetimes of the nuclear excited states. This system consists of 36 cylindrical LaBr3(Ce) ...scintillator crystals with a diameter and length of 1.5 inches each. It is suitable for measuring γ-ray emission time from a few tens of picoseconds to a few tens of nanoseconds. The data acquisition electronics of KHALA are fully digitized for both energy and timing information, resulting in the quick data processing. Detailed performance specifications, such as the energy resolution, timing response, and photopeak detection efficiency, of KHALA are presented.
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.
PHENIX reports differential cross sections of μμ pairs from semileptonic heavy-flavor decays and the Drell-Yan production mechanism measured in p+p collisions at s=200 GeV at forward and backward ...rapidity (1.2<|η|<2.2). The μμ pairs from cc¯, bb¯, and Drell-Yan are separated using a template fit to unlike- and like-sign muon pair spectra in mass and pT. The azimuthal opening angle correlation between the muons from cc¯ and bb¯ decays and the pair-pT distributions are compared to distributions generated using PYTHIA and POWHEG models, which both include next-to-leading order processes. The measured distributions for pairs from cc¯ are consistent with PYTHIA calculations. The cc¯ data present narrower azimuthal correlations and softer pT distributions compared to distributions generated from POWHEG. The bb¯ data are well described by both models. The extrapolated total cross section for bottom production is 3.75±0.24(stat)±0.500.35(syst)±0.45(global) μb, which is consistent with previous measurements at the Relativistic Heavy Ion Collider in the same system at the same collision energy and is approximately a factor of 2 higher than the central value calculated with theoretical models. The measured Drell-Yan cross section is in good agreement with next-to-leading-order quantum-chromodynamics calculations.
Innate immune responses provide the host with an early protection barrier against infectious agents, including viruses, and help shape the nature and quality of the subsequent adaptive immune ...responses of the host. Expression of ISG15 (UCRP), a ubiquitin-like protein, and protein ISGylation are highly increased upon viral infection. We have identified UBP43 (USP18) as an ISG15 deconjugating protease. Protein ISGylation is enhanced in cells deficient in UBP43 (ref. 6). Here we have examined the role of UBP43, encoded by the gene Usp18, in innate immunity to virus infection. Usp18−/− mice were resistant to the fatal lymphocytic choriomeningitis and myeloencephalitis that developed in wild-type mice after intracerebral inoculation with lymphocytic choriomeningitis virus (LCMV) or vesicular stomatitis virus (VSV), respectively. Survival of Usp18−/− mice after intracerebral LCMV infection correlated with a severe inhibition of LCMV RNA replication and antigen expression in the brain and increased levels of protein ISGylation. Consistent with these findings, mouse embryonic fibroblasts (MEF) and bone marrow-derived macrophages from Usp18−/− mice showed restricted LCMV replication. Moreover, MEF from Usp18−/− mice showed enhanced interferon-mediated resistance to the cytopathic effect caused by VSV and Sindbis virus (SNV). This report provides the first direct evidence that the ISG15 protease UBP43 and possibly protein ISGylation have a role in innate immunity against viral infection.
The calcium isotopes are an ideal system to investigate the evolution of shell structure and magic numbers. Although the properties of surface nucleons in calcium have been well studied, probing the ...structure of deeply bound nucleons remains a challenge. Here, we report on the first measurement of unbound states in 53Ca and 55Ca, populated from 54,56Ca(p,pn) reactions at a beam energy of around 216 MeV/nucleon at the RIKEN Radioactive Isotopes Beam Factory. The resonance properties, partial cross sections, and momentum distributions of these unbound states were analyzed. Orbital angular momentum l assignments were extracted from momentum distributions based on calculations using the distorted wave impulse approximation (DWIA) reaction model. The resonances at excitation energies of 5516(41)keV in 53Ca and 6000(250)keV in 55Ca indicate a significant l =3 component, providing the first experimental evidence for the ν0f7/2 single-particle strength of unbound hole states in the neutron-rich Ca isotopes. The observed excitation energies and cross-sections point towards extremely localized and well separated strength distributions, with some fragmentation for the ν0f7/2 orbital in 55Ca. These results are in good agreement with predictions from shell-model calculations using the effective GXPF1Bs interaction and ab initio calculations and diverge markedly from the experimental distributions in the nickel isotones at Z=28.
Fluorescent nanosized carbon dots (Cdots) are an emerging bioimaging agent with excellent chemical inertness and marginal cytotoxicity in comparison to widely used semiconductor quantum dots. In this ...work, we report the application of Cdots for real time bioimaging of target specific delivery of hyaluronic acid (HA) derivatives. Polyethylene glycol (PEG) diamine-capped Cdots were synthesized by the pyrolysis of citric acid in a hot solvent. The synthesized Cdots showed strong fluorescence under UV excitation with emission properties dependending on the excitation wavelength. HA–Cdot conjugates were synthesized by amide bond formation between amine groups of Cdot and carboxylic groups of HA. After confirmation of the negligible cytotoxicity of Cdots and HA–Cdot conjugates, in vitro bioimaging was carried out for target specific intracellular delivery of the HA–Cdot conjugates by HA receptor-mediated endocytosis. Furthermore, in vivo real-time bioimaging of Cdots and HA–Cdot conjugates exhibited the target specific delivery of HA–Cdot conjugates to the liver with abundant HA receptors. Taken together, we could confirm the feasibility of HA derivatives as a target-specific drug delivery carrier for the treatment of liver diseases and Cdots as a promising bioimaging agent.
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