Search results for "nuclear physics"
showing 10 items of 5307 documents
Measurement of the4He-D2 mass difference
1990
A Penning ion trap spectrometer has been used to measure the modified cyclotron frequencies of trapped4He+ and D 2 + ions. The resonances were detected by a time of flight method after ejection of the ions from the trap. We obtain a mass differenceΔm (D2-4He) = 25600331(5)·10−9 amu in acordance with published values but with a reduced uncertainty.
Penning discharge in the KATRIN pre-spectrometer
2014
The KArlsruhe TRItium Neutrino (KATRIN) experiment is a next-generation, large-scale tritium β-decay experiment to determine the neutrino mass by investigating the kinematics of tritium β-decay with a sensitivity of 200 meV/c2 using the MAC-E filter technique. In order to reach this sensitivity a low background level of 10−2 counts per second (cps) is required. A major background concern in MAC-E filters is the presence of Penning traps. A Penning trap is a special configuration of electromagnetic fields that allows the storage of electrically charged particles. This paper describes the mechanism of Penning discharges and the corresponding measurements performed at the test setup of the KAT…
Preliminary results of lifetime measurements in neutron-rich $^{53}$Ti
2019
To study the nuclear structure of neutron-rich titanium isotopes, a lifetime measurement was performed at the Grand Accélérateur National d'Ions Lourds (GANIL) facility in Caen, France. The nucleiwere produced in a multinucleon-transfer reaction by using a 6.76 MeV/u 238U beam. The Advanced Gamma Tracking Array (AGATA) was employed for the γ-ray detection and target-like recoils were identified event-by-event by the large-acceptance variable mode spectrometer (VAMOS++). Preliminary level lifetimes of the (5/2−) to 13/2− states of the yrast band in the neutron-rich nucleus 53Ti were measured for the first time employing the recoil distance Doppler-shift (RDDS) method and the compact plunger …
High-spin structure in the transitional nucleus Xe131 : Competitive neutron and proton alignment in the vicinity of the N=82 shell closure
2018
The transitional nucleus 131Xe is investigated after multinucleon transfer (MNT) in the 136Xe+208Pb and 136Xe+238U reactions employing the high-resolution Advanced GAmma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy and as an elusive reaction product in the fusion-evaporation reaction 124Sn(11B,p3n) 131Xe employing the HORUS γ-ray array coupled to a double-sided silicon strip detector (DSSSD) at the University of Cologne, Germany. The level scheme of 131Xe is extended to 5 MeV. A pronounced backbending is observed at ~ω ≈ 0.4 MeV along the negative-parity one-quasiparticle νh11/2(α = −1/2) band. The results are compared to t…
Compton imaging with AGATA and SmartPET for DESPEC
2011
DESPEC (DEcay SPECtroscopy) is a spectrometer, currently under construction, which is to be used at the FAIR (Facility for Antiproton and Ion Research) facility at GSI Darmstadt, Germany, as part of the NuSTAR (Nuclear STructure, Astrophysics and Reactions) project. Its goal is to analyse the decay of exotic nuclei produced via the Super-FRS (SUPERconducting FRagment Separator). The optimal configuration of certain elements of the spectrometer, namely a HPGe (High Purity Germanium) tracking array, is still under consideration. Work currently being carried out at the University of Liverpool using a segmented, coaxial HPGe detector (AGATA B009) and a pixelated, planar HPGe detector (SmartPET …
Enhancing the sensitivity of recoil-beta tagging
2013
Tagging with β-particles at the focal plane of a recoil separator has been shown to be an effective technique for the study of exotic proton-rich nuclei. This article describes three new pieces of apparatus used to greatly improve the sensitivity of the recoil-beta tagging technique. These include a highly-pixelated double-sided silicon strip detector, a plastic phoswich detector for discriminating high-energy β-particles, and a charged-particle veto box. The performance of these new detectors is described and characterised, and the resulting improvements are discussed.
A Mott polarimeter operating at MeV electron beam energies.
2011
We have developed a Mott electron polarimeter for the Mainzer microtron (MAMI) accelerator in Mainz, Germany. At beam energies ranging between 1.0 and 3.5 MeV two double focusing magnet spectrometers collect elastically backscattered electrons from gold targets. In spite of the small spectrometer acceptance, a sufficient statistical efficiency is achieved to provide very fast measurements if beam currents typical for experiments at MAMI are being used. High reproducibility is achieved, demonstrating that the results of asymmetry measurements are independent of the primary beam current in a range from 0.004 to 45 μA at a level of <1% relative variation. Compared to low energy polarimeters of…
A ten-fold divided total absorption Ge(Li) gamma-ray detector
1976
Abstract We have constructed a split-crystal total absorption Ge(Li) gamma-ray spectrometer and special logic electronics for rejecting Compton continuum in spectra. A 10 cm3 planar detector was divided into ten electrically separated detectors by grinding nine parallel slots on the n-surface of the detector. In operation both the n- and p-contacts are isolated from the ground. Using capacitive sharing, most of the released electrical charge is taken from the p-contact into an ordinary pulse amplifier line and analyzed. A small fraction of the charge collected at the n-strips is observed with voltage-sensitive FET-preamplifiers. The following logic electronics provides a gate pulse for the …
3He neutron spin filter at ILL
1997
Abstract The strongly spin-dependent absorption of neutrons in nuclear spin polarized 3He opens the possibility to polarize neutrons over the full-spectrum of cold, thermal and epithermal neutrons. At ILL a neutron spin filter (NSF) development started which uses the direct optical pumping of metastable 3He atoms in a 3He plasma at 1 mbar. At present 0.5 bar 1 of gaseous 3He can be polarized within 1 h. Subsequent polarization-preserving compression by a two-stage compressor system enables one to prepare NSF cells of about 300 cm3 volume in the required pressure range of several bars. A remote type of operation based on relaxation times of up to 100 h has been demonstrated in a first survey…
Simultaneous investigation of the T=1(Jπ=0+) and T=0(Jπ=9+) β decays in Br70
2017
The $\beta$ decay of the odd-odd nucleus $^{70}$Br has been investigated with the BigRIPS and EURICA setups at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center. The $T=0$ ($J^{\pi}=9^+$) and $T=1$ ($J^{\pi}=0^+$) isomers have both been produced in in-flight fragmentation of $^{78}$Kr with ratios of 41.6(8)\% and 58.4(8)\%, respectively. A half-life of $t_{1/2}=2157^{+53}_{-49}$ ms has been measured for the $J^{\pi}=9^+$ isomer from $\gamma$-ray time decay analysis. Based on this result, we provide a new value of the half-life for the $J^{\pi}=0^+$ ground state of $^{70}$Br, $t_{1/2}=78.42\pm0.51$ ms, which is slightly more precise, and in excellent agreement, with the bes…