Danilo Domenici G.Bencivenni, M.Calvetti, C.D’Ambrosio, M.Poli Lener The HPPC: a proposal for a new gaseous detector for Positron Emission Tomography with high space and time resolution

2Danilo Domenici Frascati, 22 giugno 2006 Componenti Gruppo HPPC Giovanni Bencivenni30% Mario Calvetti50% Chiara D’Ambrosio100% Danilo Domenici(Resp. Naz.)80% Marco Poli Lener20% TOT FTE 2.8 Contatti con TERA per l’organizzazione di un workshop su PET-Online

3Danilo Domenici Frascati, 22 giugno 2006 Positron Emission Tomography

4Danilo Domenici Frascati, 22 giugno 2006 Small Animal PET Motivations Humans and mice have 95% of common genes mice are a platform for simulating human diseases  1 mm FWHM (  1 mm 3 ) 6 mm FWHM (200 mm 3 ) Dedicated R&D and detectors needed to fulfill the high-resolution requirements Validation of new detectors concept is needed to access clinical cases Body weight Brain (cortex apex- temporal lobe) Heart Aorthic cannula (  ) Man~70 kg~105 mm~300 g~30 mm Mouse~20 g~6 mm~0.1 g~1 mm

5Danilo Domenici Frascati, 22 giugno 2006 How to improve PET? Space resolution Sensitivity Energy resolution Human~ 6 mmHigh needed to reject scattered events Small Animal 1 mm if low the dose can be raised not needed (negligible diffusion) Multilayer design N x (conversion layer + active detector) DOI measurement parallax correction Active detector micro-gap Resistive Plate Chamber Very high time resolution random rejection Multilayer gas detector

6Danilo Domenici Frascati, 22 giugno 2006 Random coincidences Off-center emission Parallax error Random events  2t w Time resolution Depth Of Interaction determination TOF + DOI  constraint on Z reconstruction DOI + TOF Advantages DOI: coordinate of photon interaction along the line of flight needed to correct parallax error for events far from tomography axis DOI + TOF: rough estimation of the coordinate of positron annihilation Possible solution: HPPC

7Danilo Domenici Frascati, 22 giugno 2006 HPPC Principle Of Operation glass electrode (resistive material) Parallel plate detector with resistive electrode Thin gap (~500 μm) to enhance the time resolution (~200 ps) Robust, reliable and relatively inexpensive Can be used for photon detection with suitable converter Modularity naturally allows a multi-layer design to increase efficiency No energy measurement ~300  m gold electrode (photon converter) Avalanche operation with C 2 H 2 F 4 – iC 4 H 10 – SF 6

8Danilo Domenici Frascati, 22 giugno 2006 HPPC Single Layer Design Hybrid: the anode is resistive (glass), the cathode is conductive (gold) 50μm kapton with 3μm gold film 500μm FR4 spacers outside active area gas gap 550μm float glass 50μm kapton with 5μm X-strips 50μm kapton with 5μm Y-strips HV distribution resistive coating (~1MΩ/  ) + HV GND Many single layers are stacked to realize one detector kapton circuit supports the cathode of the following layer FOV: 100x100 mm 2

9Danilo Domenici Frascati, 22 giugno 2006 HPPC Tower Design 48 stacked single RPC Readout planes are 4-fold ORed X-Y: 4 mm digital readout pitch (OR of 10 strips: 1.2 mm spatial resolution) Z: ~2 mm measurement of Depth Of Interaction (OR of 4 layers: 12 planes for parallax correction) ~200 ps time resolution ~10% photon efficiency ~100x100 mm 2 Field Of View 2 heads for coincidences detection Basic design of HPPC for high-resolution PET scanner

10Danilo Domenici Frascati, 22 giugno 2006 HPPC Prototype Parts Glass electrode with resistive coating to distribute HV Gold electrode deposited on kapton foil with FR4 frame

11Danilo Domenici Frascati, 22 giugno 2006 HPPC FLUKA Simulation Results HPPC space resolution 1.2mm physical PET resolution limit 0.5mm FWHM efficiency vs gold thickness PET and HPPC intrinsic space resolutions gold thickness limited by economical reasons

12Danilo Domenici Frascati, 22 giugno 2006 HPPC Photon Position Sensitivity hit spatial position X-Y view peak separation 2 gaussian (σ = 0.2 mm) sources separated by 1mm FWHM = 0.52 mm ~5% fraction of scattered events 10% degradation on resolution due to electron range

13Danilo Domenici Frascati, 22 giugno 2006 Stato attivita` Attivita` 2006 finanziata dalla DIREZIONE LNF (~100 k€) Acquisto circuiti readout per 4 layers Acquisto parti meccaniche Avvio laboratorio dedicato (Sistemi GAS, DAQ, HV) Previsione attivita’ 2006 Test di funzionalita`con prototipo a bassa efficienza (4 layers) Previsione attivita` Costruzione prototipo piena efficienza ( double head) Realizzazione ~500 canali di elettronica a componenti discreti Test completo con sorgente di positroni e fantoccio ad acqua

14Danilo Domenici Frascati, 22 giugno 2006 Richieste 2007 CONSUMI Circuiti readout+converter (CERN)20 k€ Elettronica di Front-End10 k€ Verniciatura resistiva vetri 5 k€ Cavi, connettori, gas, metabolismo 5 k€ TOTALE 45 k€ MISSIONI ESTERE Contatti ditte e enti (CERN, TERA) 5 k€ TOTALE45 k€