Luminosity and beam calorimeter report E. Kouznetsova, DESY

2 LAT calorimeter options L.Suszycki, Cracow Forward Calorimetry WG, Amsterdam, 31 March 2003

3 LAT luminosity measurement Essential for precise luminosity measurement is a precise angle measurement of the Bhabha scattered electrons.  L/L = needs  min = 1.4  rad The standard (TDR) setup enables only 0.2 – 0.3 mrad accuracy with the price of channels. We try The standard setup improvements and to consider alternative geometry setups: Flat LAT Stripped LAT L.Suszycki, CracowAmsterdam 31. March ‚03

4 Improved LAT geometry Improvements comparing to the Prague results: 1.Silicon sensors arranged in planes 2.Non-projective cylinders of equal height Angle reconstruction using All sensors :   =~0.9 mrad Every 4th sensor :   =~1.1 mrad Every 10th sensor :   =~1.5 mrad L.Suszycki, CracowAmsterdam 31. March ‚03 It is resonable to apply fine segmentation to a fraction of cylinders only

5 Leackage makes precision Lumi hard Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03

6 Flat LAT geometry All cylinders start at z=136 cm 7, 14, 18 or 56 cylinders assumed Conical projective geometry is kept (TDR) Sergey Kananov, Tel Aviv Angle reconstruction Gain in angle resolution = 2.5 at price of increasing of #channels of factor 56/14=4! L.Suszycki, CracowAmsterdam 31. March ‚03

7 Flat LAT shower maximum method Sergey Kananov, Tel Aviv Only rings near the shower maximum at ring #8 are significant for theta reconstruction: 1, 3, 5, 7, 10, 16 or 20 „active” rings One can reach better angular resolution with similar #channels: Uniform: 14 x 30 x 24 = => 0.18 mrad 5 rings 2-fold granulated: => 0.13 mrad 5 rings 4-fold granulated: => 0.09 mrad L.Suszycki, CracowAmsterdam 31. March ‚03

8 Silicon 1mm strips arranged in 20 cones to read r and z x 256 strips + 20 cones to read φ x 72 strips => 6560 channls in total Stripped LAT geometry Bogdan Pawlik, Cracow  =  gen -  rec (radians) vs. strip layer („cylinder”)  = ~0.9mrad at 9st layer L.Suszycki, CracowAmsterdam 31. March ‚03

9 LAT conclusions Preliminary results on alternative LAT geometry are obtained Much more MC work is necessary to get closer to the required acurracy of the angle measurement Still awaiting for the Flat Mask decision L.Suszycki, CracowAmsterdam 31. March ‚03

10 Challenges in Lumi Measurement Some studies of sensitivity to systematic uncertainties Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03

11 Method BHLUMI (Ver. 4.04) No Detector Simulation Generate an event  calculate coordinates on calorimeter  apply systematic shifts  recalculate coordinates  apply selection cuts  count events  Lumi E +, E - > 0.8 E beam Acol < 11.5 o 30 mrad < θ + < 75 mrad 30 mrad < θ - < 75 mrad Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03

12 Lin. Coeff. ≈ 0 Quadratic Coeff.: Δoffset < 200 μm Offset of Beams from Axis Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03

13 Inner Radius of Calorimeter : ΔL/L ≈ / μm Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03 Longitudinal Distance of Calorimeters : ΔL/L ≈ / mm z + - z - < 60 μm

14 Conclusions Beam Offsets: < 200 μm Inner Radius of Cal < 0.75 μm Distance of Cals < 60 μm Center-of-Mass Energy: process dependent To achieve ΔL / L ≈ : but that‘s not all yet Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03

LAT detector alignment Wojciech Wierba Institute of Nuclear Physics Cracow Poland Jerzy Zachorowski M. Smoluchowski Institute of Physics Jagiellonian University Photonics Group Cracow Poland Wojciech Wierba Cracow, PolandAmsterdam 31. March ‚03

16 LAT alignment The luminosity measurement requires precision alignment of the LAT detectors and stable, precision placement in reference to the interaction point. The beam pipe becomes as a suitable reference because the Beam Position Monitors are mounted inside the vacuum pipe. This allows us to correct the real LAT detectors position in respect to the beam position. There are four tasks: Measurement of the beam pipe dimensions in the lab. Radial metrology and mechanical design of the LAT detectors. Initial alignment of the LAT detectors in the forward region. On line system to measure displacement of the LAT detectors. Wojciech Wierba Cracow, PolandAmsterdam 31. March ‚03

17  The Photonic sensor for the z (along the beam) distance measurement: Small probe head, just end of the ~3mm fiber. Lightweight probe to be attached to the flange of the beam pipe. All electronics and laser can be placed outside the TESLA detector. Only fibers have to be feed near the LAT detector. Continuous laser beam is not necessary i.e. power fault, laser change/repair. On line system to measure displacement of the LAT detectors Wojciech Wierba Cracow, PolandAmsterdam 31. March ‚03

18 On line system to measure displacement of the LAT detectors Wojciech Wierba Cracow, PolandAmsterdam 31. March ‚03  Fine pixel CCD sensor to measure x, y and  position : The CCD detector should be glued to the rear face of the calorimeter. The laser beam can be distributed via optical fiber. The laser spot will be formed by collimator or optics. Advantages : Small and lightweight collimator/optics to be attached to the flange of the beam pipe. Laser can be placed outside the TESLA detector. Continuous laser beam is not necessary i.e. power fault, laser change/repair. Only some cables and fiber have to be feed near the LAT detector. Problems : Radiation hardness of the CCD sensor and electronics. The CCD will be placed between rear side of the LAT calorimeter and tungsten shield and probably the radiation dose will be not so high. Background from the particles. The position measurement can be done in the time slot between trains when beams are not present. The speed of the CCD sensor is sufficient to do that.

First results from silicon and diamond sensors K. Afanasiev 1, I. Emeliantchik 1, E. Kouznetsova 2, W. Lohmann 2, W. Lange 2 1 NC PHEP, Minsk 2 DESY Zeuthen

20 Test Set Up E. Kouznetsova DESY ZeuthenAmsterdam 31. March ‚03 discr delay in gate ADC PA diamond Sr or

21 Signals from 90 Sr – silicon and diamond : Si (mip) Diamond (noise) Diamond (whole  - spectra) Diamond E. Kouznetsova DESY ZeuthenAmsterdam 31. March ‚03

22 Noise level is not optimal for signal/noise separation (ENC ≈700 e) Possible solutions : Noise optimization of the existing preamplifier Switch to Amptek A250 (noise expected ≤ 350 e) New trigger scintillator matching the size of the sensor New diamond samples : Fraunhofer Institute (Freiburg) : (12 x 12 mm) 300 and 200  m Different surface treatments Prokhorov Institute (Moscow) - Dubna group Problems and further steps : E. Kouznetsova DESY ZeuthenAmsterdam 31. March ‚03

23 New Design of the Mask  For L* = 3 m performance of the mask calorimeters is doubtful  For larger L* things look easier  Question: How much L* do we need? Achim Stahl DESY Zeuthen

24 Leackage makes precision Lumi hard Fake Photons Too close to beamstrahlung Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03

25 Advantages  Luminosity: More likely to achieve 0.01 %  No fakes can scatter from mask into ECal  Vacuum much better, large orfice, bellow, valve  Space for electronics available  Better separation of outer Cal from beamstrahlung (5cm -> 8cm)  Hermetic to 3.9 mrad (was 5.5 with gaps)  Shintake monitor taken into account L* approx. 4 meters Achim Stahl DESY ZeuthenAmsterdam 31. March ‚03