Polarized antiproton at GSI: the PAX experiment

It has recently been suggested by the PAX collaboration that collisions of transversely polarized protons and antiprotons at the GSI-FAIR can be used to determine the nucleon's transversity densities from measurements of the double-spin asymmetry for the Drell-Yan process. The theoretical expectations for this observable are ill the 0.3-0.4 range at the FAIR-HESR enrgies. PAX therefore proposes to build a polarized antiproton stored beam suitable for this measurament. Polarized antiprotons will be produced by spin filtering with ail internal polarized gas target in a storage ring. The polarization buildup will be tested for the first time in an an antiproton beam at AD, CERN, and verified in a proton beam at COSY, Juelich. These tests experiments will be briefly outlined as well as the design and performance of the PAX accelerator setup and detector

Stereochemistry of serotonin receptor ligands from crystallographic data. Crystal structures of NAN-190.HBr, 1-phenylbiguanide, MDL 72222 and mianserin. HCl and selectivity criteria towards 5-HT1, 5-HT2 and 5-HT3 receptor subtypes

The crystal and molecular structures of the following serotoninergic drugs have been determined: (1) 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl]piperazine hydrobromide hemihydrate (NAN-190.HBr), C23H28N3O3+.Br-.1/2H2O, M(r) = 483.42, monoclinic, C2/c, a = 21.916 (4), b = 15.207 (2), c = 14.052 (2) A, beta = 101.56 (1) degree, V = 4588 (1) A3, Z = 8, Dx = 1.40 Mgm-3, lambda (Mo K alpha) = 0.71069 A, mu = 1.823 mm-1, F(000) = 2008, T = 295 K, R = 0.035 for 2617 observed reflections; (2) N-phenylimidocarbonimidic diamide (1-phenylbiguanide), C8H11N5, M(r) = 177.21, monoclinic, P2(1)/c, a = 9.781 (2), b = 35.040(5), c = 11.000 (2) A, beta = 97.72(1) degree, V = 3736(1)A3, Z = 16, Dx = 1.26 Mg m-3, lambda (Mo K alpha) = 0.71069 A, mu = 0.084 mm-1, F(000) = 1504, T = 295 K, R = 0.070 for 3407 observed reflections; (3) 8-methyl-8-azabicyclo[3.2.1]oct-3yl 3,5-dicholorobenzoate (MDL 72222), C15H17Cl2NO2, M(r) = 314.21, triclinic, P1, alpha = 8.480 (3), b = 9.840 (3), c = 10.158 (4) A, alpha = 90.04 (3), beta = 111.77 (3), gamma = 105.07(3) degrees, V = 755.6(5) A3, Z = 2, Dx = 1.38 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.430 mm-1, F(000) = 328, T = 295 K, R = 0.070 for 1685 observed reflections; (4) 1, 2, 3, 4, 10, 14b-hexahydro-2-methyldibenzo[c.f]pyrizino[1, 2-alpha]azepine hydrochloride (mianserin. HCl), C18H21N2+. Cl-, M(r) = 300.83, monoclinic, P2(1)/a, a = 9.014 (2), b = 14.917 (2), c = 12.412 (2) A, beta = 108.84 (1) degree, V = 1579.5 (5) A3, Z = 4, Dx = 1.26 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.237 mm-1, F(000) = 640, T = 295 K, R = 0.063 for 1493 observed reflections. A systematic structural analysis of the present compounds and others known to interact with the 5-HT1, 5-HT2 and 5-HT3 receptors allows to identify their similarities with the endogenous ligand serotonin (5-HT) and the stereochemical differences which determine selectivity for the various receptor subtypes. The pharmacophoric feature for 5-HT receptor binding is identified in a constant-length vector linking an aromatic ring with a protonated nitrogen, while specific affinities for receptorial subtypes and the nature of the effect appear to be modulated by the dimensions of the substituents at nitrogen

A HIGH INTENSITY COLD SUPERCONDUCTING JET POLARIZED TARGET

A proposed Atomic beam source with superconducting magnets in theory can provide higher intensity in atomic beam. Investigation on the formation, attenuation, focalization of different source is performed in order to provide a tools to find the right way to fulfill the requirement for more intense nuclear targets

COMPARISON OF FIELD CALCULATIONS AND MEASUREMENTS OF A SPECTROMETER MAGNET

The magnetic spectrometer of the CERN experiment NA48 uses a conventional dipole magnet with a gap of 2.40 m and a field integral of 0.83 Tm, equivalent to a transverse momentum change of charged particles of 250 MeV/c. This paper introduces the magnet and compares three-dimensional calculations of the magnetic field with the measured field map

A high intensity superconducting atomic beam source

A high intensity atomic beam source design, based on superconducting technology, is presented. The design requires compact sextupole magnets with a tapered bore and pole tip fields of 6-9 T, using superfluid helium if necessary. The cryostat housing these magnets, in addition to maintaining a stable magnet temperature with a minimal thickness along the inner bore, must also function as a cryopump for the atoms that are not focused

PRECISE DETERMINATION OF THE ELECTROMAGNETIC FORM-FACTOR OF THE PROTON IN THE TIME-LIKE REGION UP TO S=4.2 GEV2

The s dependence of the proton form factor in the time-like region has been determined up to s = 4.2 GeV2, assuming the validity of the (G(e)) = (G(m)) = (G) hypothesis. Data were taken in a dedicated experiment performed at the LEAR antiproton ring at CERN, increasing by one order of magnitude the available statistics on the proton form factor near threshold in the time-like region. Our results consist of cross section measurements of the pBARp --> e+e- reaction for different beam momenta in the kinematical range 3.6 less-than-or-equal-to s less-than-or-equal-to 4.2 GeV2. The observed s dependence of the form factor close to threshold differs appreciably from the one suggested by previous experiments

MEASUREMENT OF THE PROTON ELECTROMAGNETIC FORM-FACTOR NEAR THRESHOLD IN THE TIME-LIKE REGION

The rate of the reaction pBARp --> e+ e- has been measured in liquid hydrogen for antiprotons at momentum values between 150 and 300 MeV/c. New precise values of the proton electromagnetic form factor in the time-like region have been obtained assuming \G(e)\ = \G(m)\ in the investigated region. The q2 dependence of the form factor close to threshold is found to have a steeper slope than indicated by existing calculations based on vector dominance models