Search results for "Accelerator"
showing 10 items of 1507 documents
Herstellung und Nachweis polarisierter Elektronenstrahlen durch zweimalige Streuung von Gl�helektronen kleiner Energie (1?2 keV) an Hg-Atomstrahlen
1961
Beams of electrons of low energy (1 to 2 keV) are elastically scattered twice by atomic beams of mercury. A maximum intensity asymmetry of 200δ=31±5 was observed for double 90° scattering of 1500 eV electrons.
The AD and ELENA orbit, trajectory and intensity measurement systems
2017
This paper describes the new Antiproton Decelerator (AD) orbit measurement system and the Extra Low ENergy Antiproton ring (ELENA) orbit, trajectory and intensity measurement system. The AD machine at European Organization for Nuclear Research (CERN) is presently being used to decelerate antiprotons from 3.57 GeV/c to 100 MeV/c for matter vs anti-matter comparative studies. The ELENA machine, presently under commissioning, has been designed to provide an extra deceleration stage down to 13.7 MeV/c. The AD orbit system is based on 32 horizontal and 27 vertical electrostatic Beam Position Monitor (BPM) fitted with existing low noise front-end amplifiers while the ELENA system consists of 24 \…
Helium bubbles in metals: Molecular-dynamics simulations and positron states.
1987
By combining molecular-dynamics results for the aluminum-helium interface with positron-state calculations it is demonstrated that a positron is trapped at the surface of a He bubble in Al. The annihilation rate with Al electrons is similar to that at a clean surface, while simultaneously there is a significant annihilation rate with He electrons. This enables one to obtain a useful relation between the positron lifetime and helium densities in bubbles.
Relativistic Effects and Two-Body Currents inH2(e→,e′p)nUsing Out-of-Plane Detection
2001
Measurements of the (2)H((-->)e,e(')p)n reaction were performed with the out-of-plane magnetic spectrometers (OOPS) at the MIT-Bates Linear Accelerator. The longitudinal-transverse, f(LT) and f(')(LT), and the transverse-transverse, f(TT), interference responses at a missing momentum of 210 MeV/c were simultaneously extracted in the dip region at Q2 = 0.15 (GeV/c)(2). In comparison to models of deuteron electrodisintegration, the data clearly reveal strong effects of relativity and final-state interactions and the importance of two-body meson-exchange currents and isobar configurations. We demonstrate that such effects can be disentangled by extracting these responses using the novel out-of…
Studies of pear-shaped nuclei using accelerated radioactive beams
2013
There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments we…
Cosmology: Synchrotron radiation and quantum gravity
2004
Photons may evade a synchrotron radiation constraint on quantum gravity by violating the equivalence principle.
Multipactor Analysis in Circular Waveguides
2009
[EN] This paper mainly focuses on demonstrating that a multipactor discharge can occur within a circular waveguide operating under the fundamental TE11 circular mode. Circular waveguides are widely used in the fabrication of many passive components, in order to implement resonant cavities as well as irises to connect adjacent guides for both application domains, particle accelerators and satellite subsystems applications. Thus, we present the first study of the multipactor effect in a circular waveguide, demonstrating its existence and providing a susceptibility chart for such a structure, which will be of great interest for the better understanding of multipactor physical phenomena.
Lepton mass effects for beam-normal single-spin asymmetry in elastic muon-proton scattering
2019
We estimate the beam-normal single-spin asymmetry in elastic lepton-proton scattering without employing the ultrarelativistic approximation. Our calculation is relevant for analyses of muon scattering at energies of few hundred MeV and below -- when effects of the muon mass become essential. At such energies, the transverse polarization of the muon beam is expected to contribute significantly to the systematic uncertainty of precision measurements of elastic muon-proton scattering. We evaluate such systematics using an example of the MUSE experiment at PSI. The muon asymmetry is estimated at about 0.1\% in kinematics of MUSE and it is the largest for scattering into a backward hemisphere.
The muon magnetic moment
1981
Muon mass and muon magnetic moment are not calculabIe within the theory of Quantum Eiectrodynamics; they rather define the reference acaie in which masses and energies should be determined when muons are used to test QED or to search for anomalous muon coupiings which couid provide the "raison d'@tre" for the muon. Oniy the anomaious part of the muon magnetic moment experimentaily determined with remarkable precision I), can be oaIculated 2~" Theory and experiment agree preciseiy once corrections being appiied for hadronic and weak processes which poiiute the immaculated fieid of QED at high momentum transfers. Muon mass and muon magnetic moment are, in particular, needed for the interpreta…
The ATLAS level-1 trigger: Status of the system and experience from commissioning with cosmic ray muons
2007
The detector at CERN's large hadron collider (LHC) was exposed to proton-proton collisions from beams crossing at 40 MHz. A three-level trigger system will select potentially interesting events in order to reduce this rate to 100- 200 Hz. A trigger decision is made by the Level-1 central trigger processor (CTP) reducing the incoming rate to less than 100 kHz. The Level-1 decision is based on calorimeter information and hits in dedicated muon trigger detectors. The final Level-1 trigger system is currently being installed in the experiment with completion expected in autumn 2007. Cosmic ray data are regularly recorded as an increasing fraction of the trigger system comes online. We present a…