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News from HERMES since May 2005

News from HERMES since May 2005. Very efficient data taking in 2005. HERMES data taking . Data taking: efficiency > 98 % Spectrometer: in excellent shape Transverse polarized target: |P T | ~ 0.85 molecular frac. < 4% Main worry: P B l =+1 ~ 0.4 – 0.5 P B l =-1 ~ 0.3 - 0.4.

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News from HERMES since May 2005

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  1. News from HERMES since May 2005 60th-PRC – DESY NOV. 2005

  2. Very efficient data taking in 2005 HERMES data taking Data taking: efficiency > 98 % Spectrometer: in excellent shape Transverse polarized target: |PT| ~ 0.85 molecular frac. < 4% Main worry: PBl=+1 ~ 0.4 – 0.5 PBl=-1 ~ 0.3 - 0.4 Data taking: efficiency > 98 % Spectrometer: in excellent shape Transverse polarized target: |PT| ~ 0.85 molecular frac. < 4% 60th-PRC – DESY NOV. 2005

  3. Naïve parton model Unpolarised structure fct. Gluons are important ! BUT Full description of Jq and Jg needs orbital angular momentum 1989 EMC measured S = 0.120 0.094 0.138 ± ± Sea quarks Dqs DG Spin Puzzle News on the spin structure of the nucleon 60th-PRC – DESY NOV. 2005

  4. In LO-QCD: MC Polarised quark distributions Correlation between detected hadron and struck qf “Flavor – Separation” Inclusive DIS: Semi-inclusive DIS: Extract Dq by solving: 60th-PRC – DESY NOV. 2005

  5. First complete separation of pol. PDFs without assumption on sea polarization Du(x) > 0 Polarised opposite to proton spin Polarised parallel to proton spin Du(x), Dd(x)~ 0 No indication forDs(x)<0 In measured range (0.023 – 0.6) Polarized Quark Densities Dd(x) < 0 good agreement with NLO-QCD 60th-PRC – DESY NOV. 2005

  6. Need a longitudinal polarized deuterium target strange quark sea in proton and neutron identical fragmentation simplifies Kaon Asymmetry Inclusive Asymmetry This Work Kretzer KKP 1.20±0.06±0.03 1.103 1.111 All needed information can be extracted from data inclusive A1,d(x,Q2)and kaon AK1,d (x,Q2) double spin asym. Kaon fragmentation functions 1.43±0.36±0.15 0.392 0.150 Only assumptions used: isospin symmetry between proton and neutron charge-conjugation invariance in fragmentation Fit x-dependence of multiplicities using PDFs from CTEQ-6 Results for DQ and DS 60th-PRC – DESY NOV. 2005

  7. Direct measurement of a8 = DQ – 2DS = 0.274 ± 0.039 (0.02<x<1) SU(3) value: a8 = 0.588 ± 0.033(0.12) Earlier HERMES conclusions of unpolarised strange sea confirmed factor 2 smaller error bars Results for DQ and DS 60th-PRC – DESY NOV. 2005

  8. exclusive: all products of the reaction are detected missing energy (DE) and missing Mass (Mx) = 0 from DIS: HERMES ~0.3 The Hunt for Lq Study of hard exclusive processes leads to a new class of PDFs Generalized Parton Distributions possible access to orbital angular momentum 60th-PRC – DESY NOV. 2005

  9. unpolarized polarized quantum numbers of final state select different GPD vector mesons pseudo-scaler mesons DVCS AUT,sr,F,w AUT,sp+ AC,ALU,AUT, AUL GPDs Introduction What does GPDs charaterize? conserve nucleon helicity flip nucleon helicity not accessible in DIS 60th-PRC – DESY NOV. 2005

  10. HERMES kinematics: BH c.s. >> DVCS c.s. p + D DVCS Bethe-Heitler (BH) isolate BH-DVCS interference term non-zero azimuthal asymmetries DVCS two experimentally undistinguishable processes: transverse target spin asymmetry: 60th-PRC – DESY NOV. 2005

  11. DVCS-TTSA first model dependent extraction of Ju possible factor 2 more data on tape 60th-PRC – DESY NOV. 2005

  12. unpolarised quarks • and nucleons • q(x): spin averaged • vector charge well known longitudinally polarized quarks and nucleons Dq(x): helicity difference  axial charge known transversely polarized quarks and nucleons dq(x): helicity flip  tensor charge measuring! The 3rd Twist-2 structure function 60th-PRC – DESY NOV. 2005

  13. sensitive to the valence quark polarisation q and q have opposite sign. _ relativistic nature of quark: in absence of relativistic effects h1(x)=g1(x) Q2 –evolution: unlike for g1p(x), the gluon doesn’t mix with quark inh1p(x) (no gluon analog for spin-½ nucleon) transversely polarized quarks and nucleons dq(x): helicity flip  tensor charge measuring ! CHIRAL ODD NOT ALLOWED IN E.M. INTERACTIONS tensor charge: first moment of h1 (large from lattice QCD) angular momentum sum rule for transversity Peculiarities of transversity chiral odd FF doublehelicity flip single helicity flip 60th-PRC – DESY NOV. 2005

  14. p- unexpected large role of unfavoured FF first data for Collins FF available from Belle extraction of h1 from Hermes asymmetries 2005 data: 2 dimensional binning disentangle x (PDF) and z (FF) dependence Soon results for Kaons & p0 Transverse single spin asymmetry [PRL94(2005),012002; hep-ex0507013] Collins moment: p+ > 0 p- < 0 60th-PRC – DESY NOV. 2005

  15. DVCS exclusivity by missing mass Mx Improve Exclusivity Detect recoiling proton modify target region Detector to measure recoiling proton The end of polarized targets at HERMES 60th-PRC – DESY NOV. 2005

  16. 76% f acceptance p/p PID via dE/dx semi-incl.: 5 %® << 1% associated: 11% ® ~1% P: 135 – 1200 MeV/c study kinematical dependences detection of the recoiling proton background suppression improved t-resolution data taking 2006/2007 The HERMES Recoil Detector Build by DESY, Erlangen, Ferrara, Frascati, Gent, Giessen and Glasgow 60th-PRC – DESY NOV. 2005

  17. In total 100 Million cosmic events (03.05 - 09.05) Different sub-detectors calibration SCIFI and photon detector all fibers/strips calibration per module for Silicion Test of complete read out under realistic conditions Photon-detector: extremely stable over the whole period improved amplifier range to avoid fast aging of PMTs SCIFI-detector: GMS installed and working at 1PE (good gain monitoring) found and corrected some design flaws in readout backplanes Silicon-detector Solved several problems with common mode noise for MIPs (remember dynamic range: 1 - 50 MIP) S/N MIP: 4-5 DVCS-p: 8 - 80 Very important exercise to remove big problems smooth detector performance in 06/07 Status of the recoil detector Detector completely assembled for cosmic data taking since March 05 60th-PRC – DESY NOV. 2005

  18. Detector Residuals: Silicon SCIFI smeas = 0.372 strips /scalc = 0.223 strips Layer-efficiency: ~80% smeas = 0.379 mm/scalc = 0.235 mm Layer-efficiency: 85%-88.0% Module-efficency: ~98% Need fine tuning of alignment parameters like: use information from alignment test run for Scifi-detector accuracy: s = 80mm still ongoing effort to align all sub-detectors to each other Magnet is off – straight line as a track model First Results on detector performance 60th-PRC – DESY NOV. 2005

  19. Summary and Very successful data taking in 2005 doubled statistics of 2002-2004 with transverse polarized hydrogen target end-of-fill running with unpolarised targets 7.2 M D2 doubled statistics from Q+ paper 2.0 M Krypton and Xenon for hadron attenuation Running till 2007: Hermes would like to stick to plan switching back to e+ in the middle of the remaining period. need charged balanced data sets with high lumi and polarization to make recoil detector running a success Finalize last analysis on HERA-I data A lot of new exciting results and always more to come G1 and the corresponding QCD-fit DVCS data from pre-recoil detector phase Fragmentation functions DS from isoscalar method DVCS-TTSA -----> Ju Transversity and Sivers Analysis of HERA-II data in full swing already first publications Ready to install recoil detector in upcoming shutdown 60th-PRC – DESY NOV. 2005

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