122490179
ION-EXTRACTION POLARIMETRY FOR TENSOR POLARIZED DEUTERIUM INTERNAL TARGETS
An ion-extraction polarimeter has been developed for internal target experiments in storage rings. Here, we report on the application of such a device for a tensor polarized deuterium gas target internal to a medium-energy electron storage ring. Ions, produced by the stored electron beam, were extracted from a storage cell using electrostatic lenses and a spherical deflector, transported to a mass-analyzer, and subsequently to a 3H(d,n)α tensor polarization analyzer. The method allows determining the density-averaged nuclear polarization of the target gas, independent of spatial and temporal variations. We discuss in detail the systematic uncertainties (< 5%) associated with this technique.
122363991
Helicity structure in low- and intermediate-energy weak interaction
Abstract We report on the status of the measurements of the longitudinal polarization of positrons emitted by polarized 107 In and 12 N nuclei. Present results yield a lower limit of 306 GeV/c 2 (90 % CL) for the mass of a possible W gauge boson with predominantly right-handed couplings, if interpreted in the framework of the manifest left-right symmetric model. In addition, the helicity structure of the weak interaction is discussed on the basis of experimental results at low and intermediate energies in the leptonic, semileptonic and hadronic sectors. Whereas in the minimal manifest left-right symmetric extension of the Standard Model the results from collider experiments are superior to results from other experiments, experiments in the three sectors of the weak interaction yield complementary information on the helicity structure of the interaction if interpreted in general left-right symmetric models.
121311258
Design and construction of high-frequency transition units for polarized deuterium internal targets
Abstract Radio-frequency transition units have been developed in order to produce vector and tensor polarized atomic deuterium beams. Transitions between various hyperfine states were generated using both a medium field transition unit and a resonant cavity structure as a strong field transition unit. Tests were carried out to determine the transition efficiencies of these units as function of radio frequency power, strength of the magnetic holding field, magnetic field gradient, and for the strong field unit, also as function of the position of the atomic beam in the cavity structure. A Stern—Gerlach source equipped with a medium and a strong field unit will provide a tensor polarized deuterium beam with the highest figure of merit at the minimum number of transition units. This polarization scheme allows for rapid reversal of tensor polarization while keeping the vector polarization fixed, and vice versa. The performance of the high-frequency transition units is described well by the results of a quantum-mechanical calculation. We will demonstrate that in a realistic internal target environment the efficiencies for the transitions between the 1–4, 2–6, and 3–5 hyperfine states exceeded in all cases 90% of the theoretical maximum polarization.
103525244
Quasielastic electron scattering from polarized He-3.
118883948
FURTHER REMARKS ON THE $Sigma$ PARITY
Answers are given to some recent criticisms of the EPSILON parity determination made at the Lawrence Radiation Laboratory. (auth)
123641336
Recoil detection with a polarized He-3 target
Abstract The ultra-thin gas targets used in storage ring internal target experiments allow low energy, heavy nuclei to emerge from the target region. A detector capable of analyzing these nuclei provides unique access to many nuclear reactions. We report here the first use of such a detector in conjunction with a polarized 3 He internal target and a polarized electron beam. The results of using the detector as a luminosity monitor and as a polarimeter to measure the product of beam and target polarizations are presented. The ability to study coherent pion production via the reactions 3 He → ( e → , e ′ 3 He )π 0 and 3 He → ( e → , e ′ 3 H )π + is shown along with the ability of the detector to unambiguously separate the two- and three-body breakup channels of the reaction 3 He → ( e → , e ′p) .
1648236
The LHCb VELO: status and upgrade developments
The VErtex LOcator (VELO) is the silicon microstrip vertexing and triggering sub-detector of the LHCb experiment. It consists of a series of forward disks with the active region extending to just 8 mm from the LHC beams. The current status of the VELO is presented. Due to the high radiation environment, the VELO may have to be replaced after some years, possibly with new materials. A candidate material is Czochralski silicon. We present here promising new results on the first test beam of a large, high resistivity Czochralski microstrip silicon detector read out with LHC speed electronics. The performance was studied before and after irradiation with high energy protons. A signal to noise of over 20:1 was obtained from the detector and significant charge collection efficiencies were measured at relatively modest voltages after a fluence of 4.3/spl times/10/sup 14/ 1 MeV neutron equivalents (n/sub eq/) per cm/sup 2/. Studies using the Transient Current Technique probed the electric field within MCz test detectors and proved that MCz silicon does not type invert up until a radiation level of at least 5/spl times/10/sup 14/ 24GeV/c p/cm/sup 2/. This would mean the VELO could possibly replace, in a potential upgrade, n/sup +/-on-n DOFZ sensors and the complicated processing involved, for standard p/sup +/-on-n processing with MCz.
114023912
Performance of a wide pitch n-on-n silicon detector with floating strips
121605096
Performance of an irradiated LHCb prototype p-on-n silicon microstrip detector
Abstract A prototype silicon detector for the LHCb experiment has been irradiated non-uniformly with fluences of up to 10 15 p / cm 2 of 24 GeV protons and tested with LHC speed electronics in a test beam. After doses equivalent to one year of operation at the LHC, the detector was operational, and deteriorated after higher doses. The performance of this detector identifies particular risks associated with a p-on-n fine pitch design with a double metal layer.
15273175
The LHCb trigger strategy and performance
Precise measurements of CP-violating asymmetries, oscillation parameters and branching ratios on numerous B-decay channels will allow an overdetermination of CKM parameters, with possible inconsistencies pointing to physics beyond the Standard Model. In order to achieve this, an experiment capable of triggering on the various decay modes of B-mesons (in particular hadronic modes) is desirable. LHCb [ 1] is an experiment dedicated to such precision studies at the large hadron collider (LHC). It is designed as a forward spectrometer, because BB pairs are expected to be predominantly produced at small polar angles. An overview of the LHCb detector and trigger scheme is shown in Figure 1.
109046686
Beam incidents - High particle rate tests of an LHCb/Velo silicon strip module
L. Eklund ∗a, K. Akiba b, O. Behrendt c, M. van Beuzekom b, J. Buytaert c, P. Collins c, M. Ferro-Luzzi c, K. Hennessy d, J. Imong e aUniversity of Glasgow, Glasgow, UK. bNikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands. cEuropean Organisation for Nuclear Research (CERN), Geneva, Switzerland. dUniversity of Liverpool, Liverpool, UK eH.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom. E-mail: Lars.Eklund@cern.ch