July 2003American Linear Collider Workshop Cornell U. Development of GEM-based Digital Hadron Calorimetry Andy White U.Texas at Arlington (for J.Yu, J.Li, M.Sosebee, S.Habib, V.Kaushik)

July 2003American Linear Collider Workshop Cornell U.  GEM operation/features  First UTA GEM prototype - structure, electronics – results: cosmics, source  Multichannel prototype  Digital hadronic module ideas  Funding, collaboration Outline

July 2003American Linear Collider Workshop Cornell U. Double GEM schematic From S.Bachmann et al. CERN-EP/ Create ionization Multiplication Signal induction

July 2003American Linear Collider Workshop Cornell U. From CERN-open , A. Sharma GEM foil etching GEM field and multiplication 70  m 140  m

July 2003American Linear Collider Workshop Cornell U. GEM foil hole size

July 2003American Linear Collider Workshop Cornell U. GEM operations and features  Simple, robust  Stackable (single, double, triple)  Fast – electron signal  5ns  Relatively low voltage (~400V/foil)  Flexible – almost any anode design  Durable – no aging in extended tests  Gain 10 2 – 10 6

July 2003American Linear Collider Workshop Cornell U. Design for DHCAL using Triple GEM Ground to avoid cross-talk Embeded onboard readout

July 2003American Linear Collider Workshop Cornell U. First UTA GEM Prototype - Double GEM detector constructed using 10x10 cm 2 foils from CERN. - Single 1x2 cm 2 anode pad. - Charge preamp, then voltage amp. - Cosmic trigger, small counters, low rate! - Signal verification: no signal with (a) trigger counters displaced from anode pad, (b) air in GEM detector.

July 2003American Linear Collider Workshop Cornell U. UTA GEM-based Digital Calorimeter Prototype

July 2003American Linear Collider Workshop Cornell U. Anode pad layout 1x2 cm 2 pad

July 2003American Linear Collider Workshop Cornell U. UTA GEM prototype – high voltage

July 2003American Linear Collider Workshop Cornell U.

July 2003American Linear Collider Workshop Cornell U. GEM Prototype with preamp/voltage amp

July 2003American Linear Collider Workshop Cornell U. Amptek charge pre-amplifier

July 2003American Linear Collider Workshop Cornell U. GEM prototype – trigger counters

July 2003American Linear Collider Workshop Cornell U. Single cosmic event: upper = trigger, lower = preamp output UTA GEM Calorimeter prototype

July 2003American Linear Collider Workshop Cornell U. GEM cosmic signal distribution with Landau fit

July 2003American Linear Collider Workshop Cornell U. GEM prototype – source tests - Cs 137 source, ~1 MeV electrons - Wall of prototype thinned to allow electrons to reach ionization region of GEM, and use of thin trigger scintillators. - Rate much higher than cosmics! - Used secondary output of charge amplifier to generate ADC gate. - Study signals, noise, gain,…

July 2003American Linear Collider Workshop Cornell U. GEM prototype – source tests Source signal Noise

July 2003American Linear Collider Workshop Cornell U. Landau Distribution from Cs 137 Source Signal Amplitude (mV)

July 2003American Linear Collider Workshop Cornell U. GEM/MIP Signal Size Computation -Double GEM – applied 419V/stage -Total Ionization (C): ~93 i.p./cm  48 e - /MIP (5mm gap) -Double GEM Intrinsic Gain: G -Charge preamp sensitivity (G C ) : 0.25  V/e - -Voltage amp. X10 (G V ) -Output signal = C x G x G C x G V -Observed ~370mV signal (mean of Landau)  G = 3100 ± 20% (need better amplifier calibration)

July 2003American Linear Collider Workshop Cornell U. CERN GDD group measurements Measured UTA GEM Gain UTA Prototype

July 2003American Linear Collider Workshop Cornell U. Multichannel prototype - Next step: a 3 x 3 array of 1 cm 2 pads. - Allows one central pad with neighbors for cross-talk tests. - Use a single layer board for simplicity. - Use e.g. HELIX chip for readout. - Anode board built, prototype being reworked.

July 2003American Linear Collider Workshop Cornell U. Nine Cell GEM Prototype Readout

July 2003American Linear Collider Workshop Cornell U. GEM module ideas - Start from basic TESLA detector layout - Try simple design with GEM “drawers” slid into slots in absorber (formed from plates and spacers). - GEM layer ~6mm, readout layer ?mm. - Readout – amplifier, discriminator, register per channel close to anode pad. Multilayer board with multiple ground planes. - Working on existence proof of readout, services, module boundaries, supports, …

July 2003American Linear Collider Workshop Cornell U.

July 2003American Linear Collider Workshop Cornell U.

July 2003American Linear Collider Workshop Cornell U. TESLA – HCAL Layout

July 2003American Linear Collider Workshop Cornell U. DHCAL/GEM Module concepts Use half-size modules w.r.t. TESLA design

July 2003American Linear Collider Workshop Cornell U. Design concept for sensitive layer 3mm ionization layer

July 2003American Linear Collider Workshop Cornell U. DHCAL-GEM Layer structure - GEM layer -> 6mm - Electronics layer ~3mm - Absorber thickness 16mm x 40 layers -> ~ 4 interaction lengths for HCAL - 10x10 mm 2 cell size -> ~1.5 x 10 7 channels for DHCAL-GEM

July 2003American Linear Collider Workshop Cornell U. DHCAL/GEM Module concepts Bottom view Side view End view

July 2003American Linear Collider Workshop Cornell U. DHCAL/GEM Module concepts GEM layer slides into gap between absorber sheets

July 2003American Linear Collider Workshop Cornell U. GEM operation in magnetic field - Electrons drift along E-field lines which are ~radial in the overall detector frame. - However, B-field exists in orthogonal direction. - Forces on electron from E and B ~ equal -> so…expect ~45 deg. drift. B drift E

July 2003American Linear Collider Workshop Cornell U. Funding DoE ADR funding for year 1 completed -> Prototypes working, many simulation results (see talk by Jae Yu at this meeting) Request for two more subsequent years of ADR funding –First year of the two funded for ½ student and ½ engineer/postdoc Equipment funds through ADR + LCRD –Allows us to contemplate construction of a larger size GEM prototype

July 2003American Linear Collider Workshop Cornell U. Collaboration  Discussions with Fermilab (Physics dept.) re support for development of: - readout electronics (amplifier, discriminator, …) - electronics “layer” - GEM calorimeter stack for test beam  Agreement (June ’03) to proceed.

July 2003American Linear Collider Workshop Cornell U. Conclusions  Built and operated first prototype  Cosmic and source results – gain OK  Multi-channel prototype being built  First ideas on module design  Funding in place for another year  Collaboration with Fermilab agreed.