Search results for "Reaction"
showing 10 items of 6134 documents
Deep sub-threshold K*(892)0 production in collisions of Ar + KCl at 1.76A GeV
2013
Results on the deep sub-threshold production of the short-lived hadronic resonance K*(892)0 are reported for collisions of Ar + KCl at 1.76A GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The K*(892)0 production probability per central collision of \( P_{K^{*0}}=(4.4\pm 1.1 \pm 0.5)\times 10^{-4}\) and the K*(892)0/K0 ratio of \( P_{K^{*0}}/P_{K^0}=(1.9\pm 0.5\pm 0.3)\times 10^{-2}\) are determined at the lowest energy so far (i.e. deep below the threshold for the corresponding production in nucleon-nucleon collisions, \( \sqrt{s_{NN}}-\sqrt{s_{thr}}=-340\) MeV). The K*0/K0 ratio is compared with results of other experiments and with the pre…
The Pion Single-Event Latch-Up Cross Section Enhancement: Mechanisms and Consequences for Accelerator Hardness Assurance
2021
Pions make up a large part of the hadronic environment typical of accelerator mixed fields. Characterizing device cross sections against pions is usually disregarded in favor of tests with protons, whose single-event latch-up (SEL) cross section is, nonetheless, experimentally found to be lower than that of pions for all energies below 250 MeV. While Monte Carlo simulations are capable of reproducing such behavior, the reason for the observed pion cross-section enhancement can only be explained by a deeper analysis of the underlying mechanisms dominating proton–silicon and pion–silicon reactions. The mechanisms dominating the SEL response are found to vary with the energy under consideratio…
Proton distortion effects and meson exchange current contributions in the (e,e′p) reaction
1988
It is demonstrated that proton distortion effects could explain the relative enhancement of transverse to longitudinal response in the recent ($e,{e}^{\ensuremath{'}}p$) reactions on $^{12}\mathrm{C}$. The spin-orbit field is essential to bring about this enhancement. The role of the convection current is pointed out. Favorable contributions from pion-pair and isobar-excitation currents are also found.
Neutral currents in atomic and nuclear physics
1990
Abstract The spin structure function of the proton measured by the EMC collaboration suggests an axial isoscalar neutral current for the nucleon. I study its implications for neutral current phenomena in atomic and nuclear physics. This includes parity-violating observables for transitions between hyperfine multiplets in light muonic atoms, selected inelastic neutrino nuclear reactions and the polarization asymmetry in electron scattering for isoscalar transitions. The neutrino-induced process 7 Li → 7 Li ∗ (0.478 MeV ) is particularly favourable for neutrino reactor experiments. I find that the axial isoscalar coupling extracted from the EMC measurement increases the neutrino cross section…
Neutron removal in peripheral relativistic heavy-ion collisions
1995
We investigate the relativistic Coulomb fragmentation of $^{197}\mathrm{Au}$ by heavy ions, leading to one-, two-, and three-neutron removal. To resolve the ambiguity connected with the choice of a specific minimum impact parameter in a semiclassical calculation, a microscopic approach is developed based on nucleon-nucleon collisions (``soft-spheres'' model). This approach is compared with experimental data for $^{197}\mathrm{Au}$ at 1 GeV/nucleon and with a calculation using the ``sharp-cutoff'' approximation. We find that the harmonic-oscillator model predicting a Poisson distribution of the excitation probabilities of multiphonon states gives a good agreement with one-neutron removal cro…
High-Kfour-quasiparticle states inGd138
2011
States above the known ${K}^{\ensuremath{\pi}}={8}^{\ensuremath{-}}$ 6 $\ensuremath{\mu}$s isomer in $^{138}\mathrm{Gd}$ have been populated with the $^{106}\mathrm{Cd}$($^{36}\mathrm{Ar}$,$2p2n$) reaction at a beam energy of 180 MeV at the University of Jyv\"askyl\"a, Finland. The recoil-isomer tagging technique was utilized to correlate delayed $\ensuremath{\gamma}$-ray decays, detected in the GREAT focal plane spectrometer, with prompt decays measured in the JUROGAM II spectrometer at the target position. The lifetime of the ${K}^{\ensuremath{\pi}}={8}^{\ensuremath{-}}$ isomeric state has been remeasured as 6.2(2) $\ensuremath{\mu}$s. Two high-lying strongly coupled bands have been estab…
γ-ray spectroscopy approaching the limits of existence of atomic nuclei: A study of the excited states ofPt168andPt169
2009
Excited states in the $N=90$ and $N=91$ Pt nuclei have been investigated using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. These nuclei were populated via the reactions $^{92}\mathrm{Mo}(^{78}\mathrm{Kr},2n)$ and $^{94}\mathrm{Mo}(^{78}\mathrm{Kr},3n)$ at 335 and 348 MeV, respectively. The recoil-decay tagging technique has been used to correlate prompt $\ensuremath{\gamma}$ radiation with the characteristic $\ensuremath{\alpha}$ decays of $^{168}\mathrm{Pt}$ and $^{169}\mathrm{Pt}$. A $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ analysis has allowed a level scheme for $^{168}\mathrm{Pt}$ to be reported for the first time and the l…
Experiments with Exotic Atoms and Exotic Nuclei at GSI, Recent Developments and Future Prospects
2004
Results and new developments with exotic atoms and exotic nuclei are presented from recent experiments at GSI. The proposed European inflight facility at GSI will open up new fields of outstanding research and will simultaneously access unknown regions of nuclei with new properties. A new generation of precision experiments will be performed with stored exotic nuclei, whereby nuclear reactions with an internal target and electron scattering in a small electron-ion collider will be a great challenge.
Separation of theH2(e,e’p) structure functions up to 0.9 GeV/cmomentum transfer
1994
Longitudinal, transverse, and longitudinal-transverse structure functions for the $^{2}\mathrm{H}$(e,e'p) reaction have been determined. Measurements of the cross sections were made in-plane in nearly quasielastic kinematics spanning momentum transfers between 200 and 670 MeV/c and recoil momenta between 0 and 150 MeV/c. In addition, cross sections at momentum transfers above 800 MeV/c were measured at backward scattering angles in aligned kinematics where the response is predominantly transverse. We compared our data with both relativistic and nonrelativistic models. Our results are not consistently in agreement with any of the calculations based on these models. The disagreement between o…
The decay of105Tc to levels in105Ru
1975
Theβ−-decay of 7.6-min105Tc has been investigated byβ- andγ-ray singles and coincidence measurements. The activities have been produced by thermal-neutron-induced fission of235U or239Pu and subsequent chemical separation of the technetium fraction from the fission product mixture. AQβ-value of 3.2±0.2 MeV has been determined. In a delayed coincidence experiment the lifetime of the first excited state in105Ru at 20.55 keV has been measured to be 340±15 nsec. A level scheme of105Ru is proposed and compared with the results of recent nuclear reaction studies like104Ru(d, p) and104Ru(n, γ). From beta branching ratios to levels in105Ru, ground state spin and parity of 5/2+ can be suggested for10…