Amplificatore per rivelatore al diamante e tests R.Cardarelli e A.Di Ciaccio INFN-Roma Tor Vergata Riunione GR5 del 6/12/2012

Anna Di Ciaccio: R&D on Diamond Sensors for beam monitoring Present ATLAS BCM/BLM BCM TOF concept Collisions: in time Background: out of time 3.5 m 1.9 m BLM 2 x 6 modules Measured TOF with beam BCM module BLM module 8x8 mm pCVD Naples, November 22, 2012 Anna Di Ciaccio: R&D on Diamond Sensors for beam monitoring

Future ATLAS Diamond Pixel Monitor 24 diamond pixel modules arranged in 8 telescopes around interaction point provide Bunch by bunch luminosity monitoring Bunch by bunch beam spot monitoring Installation in July 2013 Accepted during last months as add-on to IBL DBM: 3.2<η<3.5 Naples, November 22, 2012 Anna Di Ciaccio: R&D on Diamond Sensors for beam monitoring

Anna Di Ciaccio: R&D on Diamond Sensors for beam monitoring The SuperB - SVT radmon SVT Naples, November 22, 2012 Anna Di Ciaccio: R&D on Diamond Sensors for beam monitoring

Amplificatori vs rivelatore al diamante La caratteristica fondamentale del rivelatore a diamante è l’elevata resistenza alle radiazioni e alla temperatura La naturale conseguenza è l’impossibilita di collegare l’amplificatore direttamente al rivelatore al diamante Requisito non rinunciabile del’amplificatore è l’adattamento di impedenza in ingresso ( 50 ohm) Progettazione di un amplificatore a basso rumore adattato a 50 ohm (BJT)

BJT Si v.s. SiGe BJT Si BJT performances β=τc/τt ft=1/τt N= K*τt τc= base life time τt = base transient time τt (Si) >> τt (SiGe) diffusion B E C acceleration BJT SiGe B E C

SiGe Transistor fC = KjC / 2qβ FC / fT = KπτF / βq

Amplifier, AC, (BJT SiGe, BFP740) Voltage supply 5 Volt Sensitivity 6 mV/fC noise 500 e- RMS Input impedance 50 Ohm B.W. 30 MHz Power consumption 10 mW/ch Radiation hardness 50 Mrad, 1015 n cm-2

Diamond detector under tests Mono crystal diamond thickness 0,5 mm Area 4 x 4 mm2 HV 400 Volt Dissipation power 8 μW

Current vs HV (sCVD- diamond detector)

Americium-241 + Sr-90 Am-241 Sr-90 noise

Polycrystal diamond: alfa source (log scale)

Signal from a minimum ionizing particle 20ns/div. 20ns/div.

Drift of the monocrystal diamond

Polarizzazione rivelatore diamante monocristallino . Non polarizzato mV α da 5Mev L = 4 mm polarizzato ns d = 500 μm t = d x vd

Experimental set up (Diamond orthogonal to the beam) RPC 1.2 mm thick Phenolic electrodes RPC 2mm thick phenolic electrodes Diamond detector 4*4*0.5 mm3 RPC detector 1mm gap 8mm strips pitch

Experimental set up (Diamond parallel to the beam) RPC 1mm thickness phenolik electrode (testing a thinner electrode) RPC 1.8 mm thickness phenolik electrode (Atlas standard) DVD detector 4*4*0.5 mm3 RPC 1mm gap 8mm strips pitch CAEN Digitizer mod. V1742

Diamond detector/Front-end electronics consistency checks The diamond amplitude distribution, fitting the expected Landau distribution, is used to correct the timing for the signal amplitude Front end noise distributions: - Left plot :2 stage amp followed by 1 stage amp (for ort orient) - Right plot: only 2 stage amp (for parallel orientation)

Expected diamond time resolution The diamond timing is strongly noise dependent through the relationship The following resolutions are obtained for the two orientations of the diamond Orthogonal orientation Parallel orientation σ = trise/(S/N) with trise = 10 ns (S/N)Diamondorthogonal = 13 σt = 770 ps (S/N)Diamondparallel = 145 σt = 69 ps

Combined diamond-RPC timing Assuming σcomb2= σDiam2 + σRPC2 For orthogonal orientation the overall jitter is dominated by the diamond σComb = 1 ns For parallel orientation the jitter is dominated by the RPC σComb ≈ σRPC = 0.41 ns

conclusioni Necessità di sviluppare un amplificatore ottimizzato per il rivelatore al diamante (100-200 elettroni di rumore 50 ohm di impedenza di ingresso Modificare la struttura del rivelatore per minimizzare l’effetto di polarizzazione