FastPixN an ASIC for a fast neutron telescope Maciej Kachel, IPHC Strasbourg

Outline – FastPixN Motivation and current status Chip requirements Chip structure Simulations Future plans Maciej Kachel, IPHC Strasbourg

Indirect detection of neutrons with CMOS sensor Proton flux after the converter ~ 10 3 p/s·cm 2 We are aiming for 10 6 p/s·cm 2 Maciej Kachel, IPHC Strasbourg Important features: 3 planes of detectors - > tracking and removing background Diode to record the energy Energy discrimination - > select hits only from required range of energies Motivation - telescope

Télescope à Protons de recul (TPR) Contexte de développement IPHC Maîtrise d’oeuvre de l’instrument Transfert technologique Projets court terme (3 ans) ▌ Instrumentation But : Développer un étalon primaire capable de mesurer l’énergie et la fluence suivant une procédure primaire à l’aide d’un seul outil (X 1,Y 1 ) (X 2,Y 2 ) (X 3,Y 3 ) X Y d2d2 d3d3 Tracking Principe de détection L’installation AMANDE – Accélérateur tandetron de 2 MV – Protons et deutons de 100 keV à 4 MeV – Production de champs neutroniques mono-énergétique de 2 keV à 20 MeV TPR ▌ Collaboration IPHC/IRSN-LMDN(CEA Cadarache) Θ proton neutron

▌ Quelques chiffres  3 plans MStar 320*320 pixels (1cm 2 ) + Diode SiLi  Flux ADC 12bits 20MHz (200 images/s)  ~1Gbs  FPGA CDS (2 frames), Zero suppression, Ethernet, Usb Time tag, Slow Control  GUI (webserver) Python Recoil Proton Telescope (2010-) 14 MeV : E n =13.62±0.65 MeV 17 MeV : E n =16.31±0.86 MeV ▌ Performances Fluence jusqu’à 10 6 n/cm 2 /s ITER / SPIRAL2-NFS / Hadronthérapie Fluence 10 8 n/cm 2 /s (x100) FASTPIXN (Q4 2012) TPRII (2013-) images/s

ASIC requirements Position and energy information Position - 128x128 pixels in 50 µm pitch -> 6.4 x 6.4 mm 2 Collected charge in range 30ke - – 200ke - - need ADC Fast frame readout - 10µs (inelastic events in the diode) Charge range → Big collecting diode (25µm x 25µm) → High signal to noise ratio Maciej Kachel, IPHC Strasbourg Technology: X-FAB OPTO 0.35um, 3 wafer engineering run - cheap

Speed up the readout Speed up by double readout Maciej Kachel, IPHC Strasbourg

Pixel structure Maciej Kachel, IPHC Strasbourg All transistors are Enclosed Layout Transistors to prevent radiation damage

ASIC Column structure Maciej Kachel, IPHC Strasbourg

ASIC Readout structure (basic version) Maciej Kachel, IPHC Strasbourg High speed LVDS drivers output the data from columns

Post layout simulations Maciej Kachel, IPHC Strasbourg Readout time = 50ns, 100ns between pixels Frame readout = 6 µs AMP output Charge 20 ke- 250 ke- Flash Output Q0 Q1 Q2 Q3

Linearity 20 ke ke - Noise ~ 150 e - → S/N min > 200 Post layout simulations Maciej Kachel, IPHC Strasbourg

Readout options (I) – Basic readout - read all of the data Pros: There is no lost data Cons: – Reading 0’s most of the time (with low fluxes) Maciej Kachel, IPHC Strasbourg

Readout options (II) – Read only non-zero data Pros: – Increase speed of the readout – Decrease the number of output lines/drivers – Simple with this hit rate Cons: – may cause data loss (highly improbable) Maciej Kachel, IPHC Strasbourg Both solutions will be implemented in the prototype

Summary of simulations How fast can we go (frame rate) ? 10 µs / frame -> 100k frames/s (6 μs → 160k frames/s) How fast must we go? Depends on the proton flux & rate of inelastic events in the diode The bottleneck is the readout speed The proper readout approach will be chosen after tests Maciej Kachel, IPHC Strasbourg

Summary Prototype chip submission (this week) – Matrix 32x64 – Two options of readout – Analog outputs – Test inputs in half of the matrix – Command decoder with DACs First test results expected in Q TPR II (2013-) Maciej Kachel, IPHC Strasbourg

Thank you for your attention Maciej Kachel, IPHC Strasbourg FastPixN Team : D. Husson, S. Higueret, M. Kachel

Motivation Particle detection – with use of CMOS sensor Advantages of CMOS approach: Cheap technology Flexible design of pixel matrix (ASIC – Application Specific Integrated Circuit) Accurate position of the hit Precise measurement of collected charge (with depleted substrate) Maciej Kachel, IPHC Strasbourg

Motivation Neutron detection Maciej Kachel, IPHC Strasbourg E P ~E N ·cos 2 Θ Θ proton neutron