DIRAC experiment (PS212)

  • View
    21

  • Download
    0

Embed Size (px)

DESCRIPTION

DIRAC experiment (PS212). A.Benelli. JINR, Zurich University. MESON 2012 Conference, Krakov , June, 2012. DIRAC collaboration. CERN. Tokyo Metropolitan University. Czech Technical University. IFIN-HH. Institute of Physics ASCR. JINR. Nuclear Physics Institute ASCR. - PowerPoint PPT Presentation

Text of DIRAC experiment (PS212)

Status report of the DIRAC experiment (PS 212)

DIRAC experiment (PS212)MESON 2012 Conference, Krakov, June, 2012.A.BenelliJINR, Zurich UniversityCERNKyoto University

Bern University KEK

Santiago de Compostela University

University of Messina

IHEP

INFN-Laboratori Nazionali di Frascati

SINP of Moscow State University

JINR

Nuclear Physics Institute ASCR

IFIN-HH

Institute of Physics ASCR

Tokyo Metropolitan University Czech Technical University

DIRAC collaborationZurich University

Kyoto Sangyou University

Kp :

1-loop approx. a1/2 = 0.19 + 0.02 a3/2 = -0.05 + 0.02

a1/2- a3/2 = 0.238+-0.002 P. Bttiker et al. 2004

2-loop approx. a1/2- a3/2 = 0.267 Roy-Steiner equations :

a1/2- a3/2 = 0.269 + 0.015pp :

a0 = 0.220 + 0.005a2 = -0.0444 + 0.0010

a0 a2 = 0.265 + 0.004

ChPT predicts s-wave scattering lengths:G. Colangelo et al., Nucl. Phys. B 603 (2001) 125V.Bernard, N. Kaiser, U. Meissner 1991 J. Bijnens, P.P. Donthe, P.Talavera 2004 P. Buttiker et al 2004t = (2.9 + 0.1) fst = (3.7 + 0.4) fsApp lifetime measurementobservation of Kp atoms and their lifetime measurementlong lived atoms observationThe main DIRAC aim is the accurate measurement of pp scattering lenghts and the first measurement of pk scattering lenghts

Modifided parts MDC - microdrift gas chambers, SFD - scintillating fiber detector, IH ionization hodoscope. DC - drift chambers , VH vertical hodoscopes, HH horizontal hodoscopes, Ch nitrogen Cherenkov , PSh - preshower detectors , Mu - muon detectors5Upgraded DIRAC setupDIRAC setup

targetDCstarget-SFDmagnetp (24 GeV)PSIHpA2+(nA)(NA)VH HH MDC

6p+,,,(NCC)Coulomb pairs+

0Accidental pairsp++, ,Non-Coulomb pairs(NNC)p+p(NACC)

0p+, ,(NCC)Coulomb pairsXKpp

Micro Drift Chambers

Scintillation fibres detector

Drift chambersIonisation HodoscopeTRACKING (2003: GEM-MSGC)

DC1:2x80x40 cmDC2: X,Y 80x40 cmDC3: X,Y 112x40 cmDC4: X,Y,X,Y 128x40cmBoth arms : 2016 chAnode pitch: 10mmCell:10x10cmCathode 20 mmcarbon-coated mylarAnode wires: 50 mmCopper-beryllium alloyDrift velocity: 50 mm/nsAmplitude: 1 mAPulse width: 20 nsResolution: 90 mm

18 planes : X, Y, U Area: 80x80 mmGas mixture: Ar(0.33)+ iC4H10(0.66)+H2O(0.01)Anode pitch: 2.5 mm32 wires in a planeSell size: 2.5x2 mmDrift time: 26 nsTime resolution < 1nsSpace resolution < 80mm 2 tracks resolution 1.1GeV(1.015)p>0.9GeV

Electron response Pion response Light vs momentum Heavy Gas Cerenkov detector

Aerogel

Aerogel Cerenkov detectorn=1.008 module n=1.015 module kaonsprotons

t > 0.8 fsnApk = 173+54 3.2 s90% CL

Preshower detector

Cut efficiency :12.5% e+e- 97.5% pp

e+e- subtraction 97.8% pp -K+ and +K- prompt pairs 19

Run 2008-2010, statistics with low and medium background ( of all statistics). Point-like production of all particles. The e+e background was not subtracted. Coulomb pairsAtomic pairsnon-Coulomb pairs5.3 s 26% relative error on |a1/2-a3/2|+ prompt pairs20

Run 2008-2010, statistics with low and medium background ( of all statistics). Point-like production of all particles. The e+e background was not subtracted. Coulomb pairsAtomic pairsnon-Coulomb pairsCoulomb pairsAtomic pairsnon-Coulomb pairs

Long lived atoms In order to measure an other combination of scattering length : 2a0+a2

2011-2012 data takingApp & CC and NC The A2 decay in the p-state is forbidden by angular momentum conservation. The lifetime of the A2 atom in the 2p state (2p=1.17 10-11 s) is determined by the 2p1s radiative transition with a subsequent annihilation from 1s state (1s=3 10-15 s): + + - 0 + 0*

2010-2011 : Production of A2p in Beryllium target Distribution over |QL| of p+p- pairs collected in 2010-2011 with Beryllium target with the cut QT