I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I - PDF document

PIXEL 2000 International Workshop on Semiconductor Pixel Detectors for Particles and X-Rays Genova - Porto Antico - Magazzini del Cotone (Sala Libeccio) June 5-8, 2000 I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. C. D' Ambr osio 1 , F. de Not ar ist ef ani 2 , H. Leut z 1 , D. Puer t olas 2 , E. Rosso 1 1 CERN, 2 I NFN Sect ion of Rome, I t aly

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. CERN INFN-Roma III (HIRESPET* Collaboration) Institute of Physics, Academy of Sciences-Prague Alice and LHCb exp. at CERN EP-TA2 and EP-MIC groups at CERN Industrial partners: D.E.P. (NL) Crytur Ltd. (CZ) Edgetek (FR) *http://www.roma1.infn.it/~hirespet/index.html D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. OUTLI NE � Short int roduct ion t o t he I SPA-t ube � “Convent ional” designs of gamma cameras based on I SPA-t ubes and result s � Pr esent development s : scint illat ing windows (YAP:Ce) � Conclusions and f ut ur e out look D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Position- sensitive photon detection with an I SPA- tube Photon Optical input window Phot oelect ron Photocathode H. V. (typ. 20-25 kV) VACUUM Signal out Electron- hole pairs (global analog readout) (typ. 5- 6500) (typ. 50-70 V) Bias voltage - + - + - + - + - + - + - + - + + - + - + - + - + - + - + - + - Pixel detector 500 µ m x 50 µ m Solder bump Signal out (pixel binary Pixel electronics readout) 500 µ m x 50 µ m Pixel chip developed by CERN/EP-MIC D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. The self - triggering principle detector chip electronics chip Fast, analog and global Pixel signals out (with present information chip, pixel response is binary Trigger for strobe Precise space information Immediate calibration in 2-D imaging photoelectron or energy Selection of a window in energy possible D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Detection of γ γ - rays with an I SPA- tube γ γ Input Fast (10 ns) global Photocathode window analog information (-25 kV) Rear contact YAP-detector 57 Co source Photoelectrons Binary pixel pattern read out in 10 µs 122 keV γ 's VACUUM Lead phantom Photons 30 lead-throughs Bump bonds Electronics pixel array Silicon pixel array (1024 elements) (1024 elements) Ω chip assembly developed by RD19 collabor at ion Pixel size 75mmx500mm D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. γ γ - imaging with an I SPA- tube coupled to γ γ YAP:Ce crystal detectors * P r opert ies of pur e YAP Chemical formula YAlO 3 (inert, non hygroscopic) Crystal structure Orthorhombic (no cleavage) g.cm -3 Density 5.37 Molecular weight 168.88 Z eff 34 Hardness Moh 8.6 Refractive index n at 400 nm 1.97 at 500 nm 1.95 Transparency nm 240 to >1000 Addit ional propert ies of YAP doped wit h Ce Light emission peak nm 365 Light decay (1/e) ns 27 Radiation length cm 2.7 Avr. K X-ray energy of Yttrium keV 15.2 Refractive index n at 400 nm 1.92 at 500 nm 1.91 Due t o it s pr opert ies YAP can be easily machined and opt ically polished. Ar rays of small individual element s (1mm 2 down t o 300 µ m 2 can be assembled) * Our YAP crystal detectors are produced by Crytur Ltd, Turnov, Czech Republic D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Perf ormances of I SPA- tubes in imaging The overall per f or mances of t he I SPA-t ube r ely on bot h The input window ar rangement : t he goal is t o collect as many phot oelect rons as possible while pr eser ving t he “localisat ion” of t he gamma event The anode pixel chip: t he goal is t o det ect as many phot oelect rons N pe as possible on t he det ect or plane (energy r esolut ion considerat ions) and t o get a binar y pat t ern r epr oducing t he light spot on t he phot ocat hode wit h a number of f ir ing pixels N hit (< N pe ) allowing a precise c.o.g calculat ion (analysis event per event ) D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Dif f erent possible conf igurations X- or γ γ - ray γ γ X- or γ γ γ - ray γ YAP:Ce array Phot ons YAP:Ce plate Phot ons Fibre opt ic window Phot oelect ron Phot oelect ron clust er cluster (FWHM)~crystal elements (FWHM)~2mm X- or γ γ γ γ - ray X- or γ γ γ - ray γ YAP:Ce array YAP:Ce plate Photons Phot ons Quartz window Phot oelect ron Phot oelect ron cluster clust er (FWHM)~2-2.5 mm (FWHM)>3.5 mm D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Result summary Fibr e window I SPA-t ube: ++ excellent spatial resolution from 100 µ m (array) to 300 µ m (plate) -- poor E-resolution (only a few photoelectrons) Quar t z window I SPA-t ube: ÷ acceptable spatial resolution from 500 µ m (array) to 700 µ m (plate) + good E-resolution at 122 keV from 20% FWHM (plate) to 40% FWHM (array) 200 p.e. 80p.e. see IEEE TNS, vol. 42, no6, p. 2221 and vol. 44, no5, p.1747 I SPA-t ube wit h lar ger act ive surf ace (40 mm diamet er) + The demagnification (~4) principle has been also successfully applied for gamma imaging applications, with sub-millimeter spatial resolution see NIM, A442, (2000), p.279 D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Current I SPA prototype YAP:Ce scintillating window X- or γ γ - ray γ γ X- or γ γ - ray γ γ Phot ons YAP:Ce plat e Phot ons YAP:Ce window Phot oelectron quartz window clust er Phot oelect ron cluster LHC1 * chip implementation new electronics ☛ ✝ amplifier 100 ns peaking time, globally adjustable threshold, adjustable delay line, coincidence logic and memory smaller pixel size ☛ ✝ (50x500 µ m) Electrical tests ☛ ✝ ~7.5% (150) pixels are masked (noisy) ✝✝✝✝✝✝✝✝✝✝✝✝✝✝ ☛ test input ~4900e - γ = 1710 (~85%) pixels respond with an efficiency of ~95% ≠ * The LHC1 chip has been developed at CERN by the RD19 and the EP/MIC group D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Quantum ef f iciency of S20 photocathode on YAP:Ce scintillating window 30 Q.E YAP-window HPMT Q.E Quartz-window HPMT 25 Q.E. YAP-window ISPA Q.E. Quartz-window ISPA Quantum Efficiency [%] 20 15 10 5 0 200 250 300 350 400 450 500 550 600 650 700 750 800 Wavelength [nm] P erf ect st abilit y observed over 2 years D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Energy spectra of some dif f erent sources Emissions conver t ed in t he YAP:Ce window of t he I SPA-t ube Pulse height dist r ibut ions measur ed on t he silicon chip r ear side 5000 57 Co 122 keV (FWHM) ~ 22% 4000 3000 counts [a.u.] Compt on edge P b ~ 80 keV (39 keV) + b. sc. 2000 1000 0 0 50 100 150 200 250 300 350 Number of photoelectrons 5000 60 keV (FWHM) ~ 26.5% 241 Am 4000 3000 counts [a.u.] 2000 Compt on edge (11keV) 1000 0 0 50 100 150 200 250 Number of photoelectrons D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Energy spectra of some dif f erent sources Emissions conver t ed in t he YAP:Ce window of t he I SPA-t ube Pulse height dist r ibut ions measur ed on t he silicon chip r ear side 5000 109 Cd 22 keV (FWHM) ~ 40% 4000 3000 counts [a.u.] Y escape 2000 88 keV (6.3 keV) 1000 (x20) 0 0 20 40 60 80 100 120 140 160 180 200 Number of photoelectrons 6000 5000 5.9 keV 4000 counts [a.u.] 3000 55 Fe 2000 1000 0 0 5 10 15 20 Number of photoelectrons D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Energy spectra of some dif f erent sources Emissions conver t ed in t he YAP:Ce window of t he I SPA-t ube Pulse height dist r ibut ions measur ed on t he silicon chip r ear side 4000 t wo K lines 203 Hg (72.19 keV) 3000 counts [a.u.] 2000 1000 279.2 keV 0 0 100 200 300 400 500 600 700 Number of photoelectrons D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. Photoelectron numbers versus the energies of total absorption peaks f or several gamma sources measured with the YAP- window I SPA- tube 550 y = 1.7468x - 0.203 R 2 = 0.9994 500 203 Hg γ 450 400 Number of photoelectrons 350 300 250 57 Co γ 200 109 Cd γ 150 203 Hg K 241 Am γ 100 50 109 Cd Ag X 55 Fe Mn X 203 Hg L 0 0 50 100 150 200 250 300 Energy [keV] D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. I mage of a 60 keV γ γ γ γ - source ( 241 Am) through a 2- holes (0. 35 mm φ φ φ φ ) lead collimator (5 mm thick) ~1 mm 20 k-events D. P.

I SPA-Tubes wit h YAP:Ce Act ive Windows f or X and Gamma Ray I maging. I ntensity prof ile of the two holes along the X- direction distance of the two holes = 0.90 mm on chip FWHMx meas. = 0.452 mm 40 mean1 = 2.80 mm sigma1 = 0.195 mm 35 mean2 = 3.70 mm sigma2 = 0.190 mm 30 25 20 15 10 5 0 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 c.o.g. coordinate projection x(mm) D. P.