LAT performance studies Results from Cracow (by A.Kowal, B.Pawlik, L.Zawiejski) L.Suszycki AGH University of Science and Technology Cracow

Forward Calorimetry Region with new design of the Mask LAT parameters: distance from the IP 305-325 cm radial dimensions 8-28 cm angular coverage 26.2<<82 mrad 0<<360 deg L. Suszycki Prague, 15-17 April 2004

LAT detector versions Switching the geometry: From the conical one (TDR version) to the cylindrical one. Two competitive structures of the Si/W sandwich calorimeter are considered: Si pads Si strips L. Suszycki Prague, 15-17 April 2004

Simulated LAT pad-structure Si pads/W calorimeter 16 cylinders (in r) 30 rings (in z) 24 sectors (in ) => 11520 channels analyzed angular range: 30<<78 mrad 0<<360 deg L. Suszycki Prague, 15-17 April 2004

Simulated LAT pad-structure 2 Large statistics behaviour Angular reconstruction not satisfactory – Simple reconstruction bias and resolution ~0.2 - 0.3mrad, (with 16 cylinders), can be reduced at price of large #channels L. Suszycki Prague, 15-17 April 2004

Stripped LAT description LAT consists of 30 tungsten disks Each disk has silicon strip detector attached Every second detector has either 120 radial or 64 concentric strips In total there is 2960 read-out channels L. Suszycki Prague, 15-17 April 2004

Stripped LAT reconstruction Accuracy of order 0 Stripped LAT reconstruction Accuracy of order 0.5x10-4 radian in measuring polar angle Measurement of 250GeV electron energy with accuracy 5GeV (ΔE~0.31√E) L. Suszycki Prague, 15-17 April 2004

Stripped LAT - Bhabha events Measurement of the scattered electron energy with accuracy 7GeV (ΔE~0.44√E) Egen - Erec L. Suszycki Prague, 15-17 April 2004

Stripped LAT - Bhabha events 2 Reconstruction of energy of the back-to-back electron pair E (GeV) L. Suszycki Prague, 15-17 April 2004

Stripped LAT - Bhabha events 3 Reconstruction of theta angle of the back-to-back electron pair Gen. Rec. θ (mrad) L. Suszycki Prague, 15-17 April 2004

Stripped LAT - Bhabha events 4 Acolinearity θL – θR (mrad) L. Suszycki Prague, 15-17 April 2004

Stripped LAT - Bhabha events 5 Angle reconstruction accuracy ~0 Stripped LAT - Bhabha events 5 Angle reconstruction accuracy ~0.09 mrad θgen – θrec (mrad) L. Suszycki Prague, 15-17 April 2004

Beamstrahlung background No photons are seen in LAT (θ>26 mrad) L. Suszycki Prague, 15-17 April 2004

Beamstrahlung background 2 L. Suszycki Prague, 15-17 April 2004

Beamstrahlung background 3 Pairs from beamstrahlung in LAT angular range L. Suszycki Prague, 15-17 April 2004

Beamstrahlung background 4 Energy from beamstrahlung in LAT angular range Background may be present at rmin (deg) and azimuthal angle 0/180 degrees (deg) L. Suszycki Prague, 15-17 April 2004

Summary LAT with pads: reconstruction algorithm to be improved or changed completely Stripped LAT: seems ok Bhabha events: in progress Beamstrahlung: needs detector simulation L. Suszycki Prague, 15-17 April 2004

The end Thank you

Notices Stripped LAT: E_rec = 60.79*E_seen Generated 20 000 events, reconstr. 9800 (26 – 86 mrad) Beamstrahlung: TDR, FC Proposal 20-40 TeV/bx, Jeju 20 TeV A.Stahl 500 TeV/bx photons, 100 TeV/bx pairs (in BeamCal 5 TeV/bx and 20 TeV/bx) – Zeuthen Nov 2002 L. Suszycki Prague, 15-17 April 2004

Reconstruction results (512ch) L. Suszycki Prague, 15-17 April 2004