Danilo Domenici

G.Bencivenni, M.Calvetti, C.D’Ambrosio, M.Poli Lener

The HPPC: a proposal for a new The HPPC: a proposal for a new gaseous detector for Positron gaseous detector for Positron

Emission Tomography with Emission Tomography with high space and time resolution high space and time resolution

2 Danilo DomeniciFrascati, 22 giugno 2006

Componenti Gruppo HPPC

Giovanni Bencivenni 30%

Mario Calvetti 50%

Chiara D’Ambrosio 100%

Danilo Domenici (Resp. Naz.) 80%

Marco Poli Lener 20%

TOT FTE 2.8

Contatti con TERA per l’organizzazione di un workshop su PET-Online

3 Danilo DomeniciFrascati, 22 giugno 2006

Positron Emission Tomography

4 Danilo DomeniciFrascati, 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 mm3)

6 mm FWHM (200 mm3)

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

5 Danilo DomeniciFrascati, 22 giugno 2006

How to improve PET?Space

resolutionSensitivity

Energy resolution

Human ~ 6 mm High

needed to reject

scattered events

Small Animal

1 mmif 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

6 Danilo DomeniciFrascati, 22 giugno 2006

Random coincidencesOff-center emission

Parallax error

Random events 2tw Time resolution

Depth Of Interaction determinationTOF + 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

7 Danilo DomeniciFrascati, 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

~300m

gold electrode (photon

converter)

Avalanche operation with

C2H2F4 – iC4H10 – SF6

8 Danilo DomeniciFrascati, 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 mm2

9 Danilo DomeniciFrascati, 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 mm2 Field Of View

2 heads for coincidences detection

Basic design of HPPC for high-resolution PET scanner

10 Danilo DomeniciFrascati, 22 giugno 2006

HPPC Prototype Parts

Glass electrode with resistive coating to

distribute HV

Gold electrode deposited on kapton foil with FR4

frame

11 Danilo DomeniciFrascati, 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

12 Danilo DomeniciFrascati, 22 giugno 2006

HPPC Photon Position Sensitivity

hit spatial positionX-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

13 Danilo DomeniciFrascati, 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`2007+2008

Costruzione prototipo piena efficienza (48 + 48 double head)

Realizzazione ~500 canali di elettronica a componenti discreti

Test completo con sorgente di positroni e fantoccio ad acqua

14 Danilo DomeniciFrascati, 22 giugno 2006

Richieste 2007

CONSUMI

Circuiti readout+converter (CERN) 20 k€

Elettronica di Front-End 10 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€

TOTALE 45 k€