Search results for "Proton"

Tests and developments of the PANDA Endcap Disc DIRC

2016

The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) requires excellent particle identification. Two different DIRC detectors will utilize internally reflected Cherenkov light of charged particles to enable the separation of pions and kaons up to momenta of 4 GeV/c. The Endcap Disc DIRC will be placed in the forward endcap of PANDA's central spectrometer covering polar angles between 5° and 22°. Its final design is based on MCP-PMTs for the photon detection and an optical system made of fused silica. A new prototype has been investigated during a test beam at CERN in May 2015 and first results will be presented. In addition a new synthetic fused silica material…

Towards an Improved Measurement of the Proton Magnetic Moment

2017

The BASE collaboration performed the most precise measurement of the proton magnetic moment. By applying the so-called double Penning-trap method with a single proton a fractional precision of 3.3 parts-per-billion was reached. This article describes the primary limitations of the last measurement and discusses improvements to reach the sub-parts-per-billion level.

2012

A new apparatus has been designed that aims at a direct precision measurement of the g-factor of a single isolated proton or antiproton in a Penning trap. We present a thorough discussion on the trap design and a method for the experimental trap optimization using a single stored proton. A first attempt at the g-factor determination has been made in a section of the trap with a magnetic bottle. The Larmor frequency of the proton has been measured with a relative uncertainty of 1.8◊10 6 and the magnetic moment has been determined with a relative uncertainty of 8.9◊10 6 . Ag-factor of 5.585696(50) has been obtained, which is in excellent agreement with previous measurements and predictions. F…

Measurement of theZZProduction Cross Section and Limits on Anomalous Neutral Triple Gauge Couplings in Proton-Proton Collisions ats=7  TeVwith the AT…

2012

A measurement of the ZZ production cross section in proton-proton collisions at root s = 7 TeV using data corresponding to an integrated luminosity of 1.02 fb(-1) recorded by the ATLAS experiment a ...

Precision Measurement ofLi11Moments: Influence of Halo Neutrons on theLi9Core

2008

The electric quadrupole moment and the magnetic moment of the 11Li halo nucleus have been measured with more than an order of magnitude higher precision than before, |Q| = 33.3(5) mb and mu = +3.6712(3)muN, revealing a 8.8(1.5)% increase of the quadrupole moment relative to that of 9Li. This result is compared to various models that aim at describing the halo properties. In the shell model an increased quadrupole moment points to a significant occupation of the 1d orbits, whereas in a simple halo picture this can be explained by relating the quadrupole moments of the proton distribution to the charge radii. Advanced models so far fail to reproduce simultaneously the trends observed in the r…

Fits of the baryon magnetic moments

1981

A model for the mass-number independence of the antiproton annihilation on nuclei at low energies

2001

Abstract A simple model explaining the recently observed approximate independence of the annihilation cross section on light nuclei at low energies is proposed. The salient idea is based on the realization that the π s from the annihilation on a nucleon have energies in the region of the Δ (1232) resonance. The coherent propagation of these π s through the excitation of several Δ resonances results in a destructive interference explaining why the annihilation of antiprotons in nuclei is suppressed. This model suggests a very effective way to produce “ Δ matter” with several Δ resonances in interaction.

Gamow-Teller strengths in proton-rich exotic nuclei deduced in the combined analysis of mirror transitions

2005

Isospin symmetry is expected for the T-z=+/- 1 -> 0 isobaric analogous transitions in isobars with mass number A, where T-z is the z component of isospin T. Assuming this symmetry, strengths of analogous Gamow-Teller (GT) transitions within A=50 isobars were determined from a high energy-resolution T-z=+1 -> 0, Cr-50(He-3,t)Mn-50 study at 0 degrees in combination with the decay Q value and lifetime from the T-z=-1 -> 0, Fe-50 ->Mn-50 beta decay. This method can be applied to other pf-shell nuclei and can be used to study GT strengths of astrophysical interest.

Nonquenched Isoscalar Spin-M1Excitations insd-Shell Nuclei

2015

Differential cross sections of isoscalar and isovector spin-M1 (0(+)→1(+)) transitions are measured using high-energy-resolution proton inelastic scattering at E(p)=295  MeV on (24)Mg, (28)Si, (32)S, and (36)Ar at 0°-14°. The squared spin-M1 nuclear transition matrix elements are deduced from the measured differential cross sections by applying empirically determined unit cross sections based on the assumption of isospin symmetry. The ratios of the squared nuclear matrix elements accumulated up to E(x)=16  MeV compared to a shell-model prediction are 1.01(9) for isoscalar and 0.61(6) for isovector spin-M1 transitions, respectively. Thus, no quenching is observed for isoscalar spin-M1 transi…

Fine structure in the beta-delayed proton decay of 33Ar

1996

9 pages, 2 figures, 2 tables.-- PACS nrs.: 21.60.Cs; 23.40.−s; 27.30.+t; 29.30.Ep.