Photoproduction of K + L(1405) near threshold

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Photoproduction of K + L(1405) near threshold. Main features of the reaction Kinematics K + meson identification TAPS calibration for charged particles MC simulation conditions Results Summary. V.L. Kashevarov, CB@MAMI Collaboration Meeting, Basel 2006. g p → K + L (1405). - PowerPoint PPT Presentation

Text of Photoproduction of K + L(1405) near threshold

  • Photoproduction of K+L(1405) near thresholdMain features of the reactionKinematicsK+ meson identificationTAPS calibration for charged particlesMC simulation conditionsResultsSummaryV.L. Kashevarov, CB@MAMI Collaboration Meeting, Basel 2006

  • g p K+ L(1405)L(1405) (or L*) mass = 1406.5 MeVThreshold = 1454.97 MeVFull width = 50 2 MeVL* decay modes: So po (33%), S+ p- (33%), S- p+ (33%)Final particles to be detected: (1) K+ L* { So [ L ( po n ) g ] po } 11.9% (2) K+ L* { So [ L ( p- p ) g ] po } 21.1% (3) K+ L* { S+ ( p o p ) p- } 17.2% (4) K+ L* { S+ ( p+ n ) p- } 15.8% (5) K+ L* { S- ( p- n ) p+ } 33.3%

  • Kinematics E g = 1455 1507 MeV

    Ekin (MeV)Q (deg)Ekin (MeV) vs Q (deg)K+

  • (1) So { L (po n) g } poEkin (MeV) vs Q (deg) po g po n

  • (2) So { L (p- p) g } poEkin (MeV) vs Q (deg) g p- po p

  • (3) S+ (p o p) p-Ekin (MeV) vs Q (deg) po p- p

  • (4) S+ (p+ n) p-Ekin (MeV) vs Q (deg) n p-p+

  • (5) S- (p- n) p+Ekin (MeV) vs Q (deg) n p-p+

  • K+ meson identification in TAPSCluster energy (MeV)Time of flight (ns)

  • TAPS calibration for charged particles p pK+K+p+p+Cluster Energy (MeV)E kin (MeV)E kin (MeV)Time of flight (ns)

  • TAPS calibration for charged particles p pK+K+p+p+Cluster Energy (MeV)E kin (MeV)E kin (MeV)Time of flight (ns)

  • MC simulation conditionsEndpoint tagger: E g = 1455 1507 MeVTagger bin = 2 MeVLadder = 800 kHz (Main tagger from 900 MeV)Tagging efficiency = 0.4Live time = 60%LH2 target length = 5 cmFront of TAPS Center of target = 120 cmOld PID and MWPC, but without any materials in forward directionNo Cherenkov detectorTotal cross section for 1480 MeV = 100 nb

  • ResultsE K+ = F (E cluster)E K+ = F (ToF)E g = 1475 MeVMM ( g, K +) - M L* (MeV)

  • ResultsMM ( g, K +) - M L* (MeV)(1) K+ L* { So [ L ( p o n ) g ] p o } Partial contribution = 0.8% (0.06%)(2) K+ L* { So [ L ( p - p ) g ] p o } 1.8% (0.13%)(3) K+ L* { S+ ( p o p ) p- } 4.8% (0.25%)(4) K+ L* { S+ ( p+ n ) p- } + (5) K+ L* { S- ( p - n ) p+ } 2.8% (0.45%) 10.2% (0.9%)

  • Results : InvMass L ( po n ) So ( po n g ) L* ( po n g po ) (1) K+ L* { So [ L ( p o n ) g ] p o } Partial contribution = 0.6% (2) K+ L* { So [ L ( p - p ) g ] p o } 0.8% 1.4% L ( p- p ) So ( p- p g ) L* ( p- p g po )

  • Results : InvMass(3) K+ L* { S+ ( p o p ) p- } 2.4% (4) K+ L* { S+ ( p+ n ) p- } + (5) K+ L* {S- ( p - n ) p+ } 4.2% 6.6% S+ ( p+ n ) + S- ( p - n ) L* ( p+ n p- ) S+ ( po p ) L* ( po p p- )

  • SummaryThe best way for investigation of the reaction is to measure MM( g ,K+);Coincidences between K+ and two or three final state particles are needed to suppress background;Endpoint tagger would be very useful;TAPS detector allows to do a good identification of K+ mesons for cluster size < 3 and cluster energy < 200 MeV;Missing mass resolution: 25 MeV;Detection efficiency: 10.2 %;Expected yield: 0.1 events/nb/h.