LCcal a Calorimeter prototype for future Linear Colliders

LCcal*: a Calorimeter prototype for future Linear Colliders TALK SUMMARY • Design principles • Prototype description • Construction details • Test Beam results • Conclusions and Future plans * Contributors (Como, ITE-Warsaw, LNF, Padova, Trieste): M. Alemi, A. Anashkin, M. Anelli, M. Bettini, S. Bertolucci, E. Borsato, M. Caccia, P. C, C. Fanin, J. Marczewski, S. Miscetti, B. Nadalut, M. Nicoletto, M. Prest, R. Peghin, L. Ramina, F. Simonetto, E. Vallazza …. 2003 10 06 P. Checchia Como 8 th ICATPP 1

Design principles From the LC Physics requirements: Tesla TDR solutions: Alternatives: • Si W • Shashlik (thanks to CALEIDO) • Cristals • Fully compensating Ecal+Hcal Proposed solution: Keep Si. W advantages (flat geometry, high granularity) Erec. not from Si but from Scintillator-WLS fibers Reduce (factor >10) the number of channels 2003 10 06 P. Checchia Como 8 th ICATPP 2

Prototype description Pb/Sc + Si • 45 layers • 25 × 0. 3 cm 3 Pb • 25 × 0. 3 cm 3 Scint. : 25 cells 5 × 5 cm 2 • 3 planes: • 252. 9 ×. 9 cm 2 Si Pads • at: 2, 6, 12 X 0 Scintillation light transported with WLS σ tail fibers: Coupled with clear fibers (to PM) Cell separation with grooves in Sc. plates with Tyvec strips inside 2003 10 06 P. Checchia Como 8 th ICATPP 3

Prototype (cntd) 3 Si planes Goal: shower-shower separation, position measurement, e/h identification: • Pad dimension< shower dimension: . 9 x. 9 cm 2 • Longitudinal sampling: 3 planes • Analogic RO VA hdr 9 c from IDEas • See A. Bulgheroni’s talk for details Pad diode ac(old)dc(new) coupled Actual design: - Detector: 6 x 7 pads - Plane: 3 x 2 detectors 2003 10 06 pcb contact with conductive glue P. Checchia Como 8 th ICATPP 4

Construction details: Scintillator • 3 mm Kuraray SCSN-61 (25 x 25 cm 2) • 3 mm Bicron BC-408 (25 x 25 cm 2) Machined with vacuum plate as holder Whole Production (>50 tiles) done in september 2002 2003 10 06 P. Checchia Como 8 th ICATPP 5

Fibers: Kuraray 1 mm d. Y 11 300 ppm multicladding Face polished and aluminized by sputtering To make the 2. 4 cm radius curvature : middle temperature(500 -700) oven Splicing with optical glue and a supporting tube : stable in >30 day time 2003 10 06 P. Checchia Como 8 th ICATPP 6

Detector Assembling: 45 Layers calorimeter prototype completely built in 2002 Fibres grouped into 25 x 4 bundles making a 4 -fold longitudinal segmentation. Slots for the insertion of the 3 Si pad planes (Motherboard). 2003 10 06 Mechanical support for Photomultipliers Checchia Como 8 th ICATPP in P. the 3 x 3 central cells 7

Test beam activity after a 2002 pre test with the 1 st layer only (2. 1 X 0) at CERN • two runs at Frascati Beam Test Facility (n × 50 – 750 Me. V) detector LINAC Beam 1 -500 m. A tunable W target: 1. 7, 2. 0, 2. 3 X 0 W slits 450 magnet it is possible to tune the multeplicity. . . • run at CERN SPS H 6 beam line (e/ 5 – 150 Ge. V) All tests: two beam position monitors (telescope) put in front of the calorimeter. - Each detector consisting of 400 x–y Si strips with a pitch of 240 m - They cover the central area of the prototype (9. 5 cm 2) trigger 2003 10 06 beam LCcal

Test beam activity : detector calibration define ‘cell’ as the calibrated sum of the 4 longitudinal layers on the same lateral position: Ci=bi j=1, 4 aj. Lij L 4 L 3 (4 -1+9 -1+16 parameters) L 2 L 1 process in two steps: Ci Si L 3 • equalise the layer response at the same incoming energy Lij=bk/bi Lkj • minimise the Energy spread on the sum of 9 cells (iterative process) aj | min. width Ecal= n=1, 9 Cn 2003 10 06 P. Checchia Como 8 th ICATPP Si L 2 Si L 1 9

es t F Good linearity vs molteplicity 1 e 2 e 3 e- t BT E E Test beam results: Linearity and Energy Resolution 11. 5% E Ebeam (Me. V) 02 0 2 B T rn N >5. 1 /layer →Cal(45 layers) ~ e phe C 250 Me. V/Mip ~ 800 Npe/Ge. V OK also @ BTF (E ~500 Me. V) 2003 10 06 1. Photoelectron statistics negligble 2. Stocastic Term 11. 5% as in MC 3. Light disuniformity <<10% Effects on resolution to be measured at SPS (August 2003) P. Checchia Como 8 th ICATPP 10

Test beam results: Linearity and Energy Resolution E E Cern TB 2003 Ecal (Ge. V) pm saturates e- confirmed at high energy !!! 11. 1% E Ebeam (Ge. V) 75 Ge. V 15 Ge. V e- 2003 10 06 Ecal (Ge. V) P. Checchia Como 8 th ICATPP Ecal (Ge. V) 11

y pad Si L 2 (cm) Test beam results: Si pad detector (Position Meas. ) Cern TB 2003 30 Ge. V electrons y telescope (cm) = 2. 4 5 m m = 2. 1 6 m = 3. 2 7 m m Si L 2 Si L 1 2003 10 06 e- Si L 1+L 2 m =1. 76 mm Si L 3 P. Checchia Como 8 th ICATPP y pad –y telescope (cm) 12

Test beam results: Si pad detector (Position Meas. ) PRELIMINARY analysis: pad noise subtraction not optimised Position resolution 2. 5 mm not far from Monte Carlo 10 Ge. V electrons 10 Ge. V simulated electrons 2003 10 06 =2. 5 mm P. Checchia Como 8 th ICATPP 13

Test beam results: uniformity in (light) Energy response Cern TB 2003 disuniformity < 2% correction from pad reconstruction can be applied! x telescope ± 2% PRELIMINARY: cell border effects dominated by residual miscalibration x pad x (cm) ± 2% x telescope x pad Ecal (Ge. V) y(cm) Ecal (Ge. V) 30 Ge. V e- Cj Cj-1 x (cm) 14

Test beam results: ( e/ rejection) the redundancy of the information on the linear/lateral shower development makes the rejection very easy (difficult to quantify below 10 -3 due to beam contamination) 30 Ge. V e 30 Ge. V Cern TB 2003 30 Ge. V e 30 Ge. V E Si pad Layer 1 Si pad Layer 2 30 Ge. V E cal Layer 1 50 Ge. V e 75 Ge. V 30 Ge. V e- shower variance: 2003 10 06 15

Test beam results: Si Pad two particle separation exhaustive analysis not fully accomplished Two electrons with energy 750 Me. V X silicon chambers BT F Y silicon chambers First layer t tes Second layer NB: not fully equipped+ problematic channels 2003 10 06 Third layer P. Checchia Como 8 th ICATPP 16

Conclusions and Future plans • A calorimeter prototype with the proposed technique has been built and fully tested. All the results are preliminary. • Energy and position resolution as expected: E/E ~11. -11. 5% / E, pos ~2 mm (@ 30 Ge. V) • Light uniformity acceptable. • e/ rejection very good ( <10 -3). • Two particle separation results coming soon. • Next steps: include a calorimeter made following this technique into the general LC simulation and Pattern recognition. • Combined test with Hcal (? ) 2003 10 06 P. Checchia Como 8 th ICATPP 17

backup 2003 10 06 P. Checchia Como 8 th ICATPP 18

Detector Assembling: 2003 10 06 P. Checchia Como 8 th ICATPP 19

PM’s Fibres with PM support structure Fibres faced to PMs Piani Si 2003 10 06 P. Checchia Como 8 th ICATPP Scintill. LCCAL in test @ BTF (Frascati) 20

Test beam results CALORIMETER (2. 1 X 0) 4 layers m. i. p. →check light output and uniformity in Light collection: Ratio signal/sigma →lower limit for photoelectrons Nphe>5. 1 /layer → cal(45 layers): >220 phe/m. i. p. good uniformity: Simulated Light collection disunifority(20%) 2003 10 06 P. Checchia Como 8 th ICATPP 21