Readout Electronics for high-count-rate high-resolution X-ray spectroscopy Luca Bombelli, R&D Director XGLab s.r.l., Via Francesco D’Ovidio 3, I-20131 Milano, Italy , info@xglab.it 14 April 2015, Pisa ERDIT

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Expertise Detector Low Noise Front-End Processing and MCA Software Primi due cruciali per performance (noise), secondi due per flessibilità Processing and MCA TWINMIC ELETTRA Software

SUMMARY CUBE: new Front-End readout for detectors DPP: High Rate X-ray spectroscopy (digital shaping) VERDI-3: Versatile Electronics for Multichannel systems High speed, 1-D Gamma Camera for Prompt-gamma imaging

ASICs: CUBE A full CMOS preamplifier can replace the single front-end JFET SDD CUBE Advantages: High signal level at the output of the module. No sensible loop outside the module. Possibility to drive “long” connection. Preamp Compactness Superior performance respect to all the front-end JFET available at short shaping time.

Comparison with available JFET 0.2us Measured energy resolution with identical SDDs 0.1us

Spectroscopy performances of CUBE connected to a SDD 1μs shaping time (optimum) ENC = 3.7e- rms 55Fe spectrum 123 eV FWHM Commercial analog shaper: 7th-order Semi-Gaussian complex-pole

Spectroscopy performances of CUBE connected to a SDD 64mm2 SDD Squared Ballistic deficit Temperature CUBE also suited for HPGE, SiLi and RTD No worsening at cryogenic temperature

Digital Pulse Processor Platform Optimized for CUBE Input stage optimized for CUBE output (dynamic range, gain, etc…) Provide best possible energy resolution Provide good performance at fast count-rate (peaking down to 120ns) Handle very high input count-rate (ICR up to 3Mcps) US patent: 7763859, 8039787, 7855370, 7807973

SDD+ CUBE + DPP performances Energy Resolution Detector SDD CUBE preamplifier Temp= -60°C Collim. Area = 50mm2 Signal rise = 300ns Flattop = 330 ns

DPP performances Energy Resolution

DPP performances 98.5% dead-time 55Fe spectra 55Fe + X-ray tube spectra

DPP customization Supply: +/- 5V Power: 1.5W 10 cm Compact single-board design, low power Design to be reconfigurable and adaptive to several applications Scalable to multi-cannel (in days chain mode) High-performance 16-bit 105-MHz ADC. High performance FPGA Possibility to add list mode operation USB2.0 or Ethernet TCP/IP Simple DLL libraries, or LabView High throughput performance Automatic Adaptive Filtering Mode

VERDI-3 Silicon Lithium Detectors Silicon detectors (PIN, SDD, SSDD for gamma scintillator) Germanium Detectors (Segmented, Coaxial, Planar) PMTs (or SiPM) Multi-channel readout of different detector for several applications

VERDI Module 8 complete analog channels Single +5V power supply USB2 interface, driver and DLL

Analog channel 2 polarity: electrons, holes 15 gains: 20 - 300mV (CSA range) 8 shaping times: 0.25 - 8μs Selectable outputs: 1-pole pulse, 7 poles Shaper, PKS, KILL BLH compensating detector leakage current: 0,1pA - 11nA Variable SR, Gain, Bandwidth

XRF application with SDDs VERDI config. Pulsed-reset Exernal preamp. Internal shaper, PKS. Energy range = 0 - 40 keV Output = Multiplexer Fe55 Source 25mm2 single-anode SDD Temp. = -30°C

Application with Ge VERDI config. continuous reset Input cap. = 50pF JFET gm = 15mS Range = 3keV - 10MeV Output = 1-pole pulse Resolution [eV] Irradiation with a Co-57 source Active volume = 34,2 cm2 Temperature = 70K Digital filter Rise Time [μs]

Application with Si(Li) VERDI config. Pulsed-reset system Input cap. = 2pF JFET gm = 11mS Output = 1-pole pulse Resolution [eV] Fe-55 source Temperature = 70K Detector area = 1,1cm2 Digital filter Rise Time [μs]

VERDI-3 Experimental setup Detector main characteristic: Structured HPGe monolithic detector Thickness 11mm 16 pixel with 6mm pitch Pixel area 36mm2 Operation close to LN2 temperature VERDI-3 HPGe crystal Energy resolution with a Americium 241 source Pixel with higher leakage current

Prompt Gamma imaging with a Slit Camera High counting statistics Simple design, reduced cost and limited footprint Suitable to the measure of a single pencil beam Most correlated energy range: 3 MeV ÷ 6 MeV

Specifications and design choices Requested sensitivity: 15 cGy Volume: 500 cm3 LYSO (7.1 g/cm3 ) Event rate: 40 MHz Pixelated design to reduce the rate in the single channel Channel rate = 1 MHz Fast crystal: τLYSO = 41 ns Fast photo-detectors: SiPM Fast electronics Visible light output face

The prototype Back view Front view SiPM custom array: 7 SiPMs with 3 x 3 mm2 active area LYSO slab: 31.5 x 100 x 4 mm3 Polished surfaces Prompt Gammas LYSO slabs in aluminum case (only 1 row of 20 slabs mounted) Motherboard and backplane board

Calibration Clinical beam current Slow mode maximum event rate: 50 kHz A/D conversion of pulse amplitude Spectrum and energy calibration Clinical beam current Fast mode maximum event rate: 1 MHz 3 MeV 6 MeV Valid event Events discarded Counting of valid events Real-time profile reconstruction

Spectrum in slow operation mode (single channel) No collimator in place Beam energy: 100 MeV Beam current at nozzle: 44 pA Measurement time: 3 min T = 25 °C

Experimental results: spectra in slow mode and thresholds setting Energy calibration made with 137Cs source and the double escape peaks of Oxygen and Carbon Exponential fitting to take into account SiPM saturation

Target shift detection Beam d2 Reference position (0 mm) Beam energy: 100 MeV Energy range: 3 ÷ 6 MeV Time of acquisition: 10 s

Target shift detection Beam d2 Reference position (0 mm) Beam energy: 100 MeV Energy range: 3 ÷ 6 MeV Time of acquisition: 10 s 1 mm

Target shift detection Beam d2 Reference position (0 mm) Beam energy: 100 MeV Energy range: 3 ÷ 6 MeV Time of acquisition: 10 s - 1 mm

Target shift detection

Thank you

Leakage and photons CUBE output 55Fe signal 30 ns SDD connected

CUBE operation over temperature Pulsing SDD Ring1 200 ns 300 K 50 K CUBE Rise-time < 40 ns Irradiating with LED 300 K 3 us 50 K 300 ns SDD drift time: 300ns @ 50K 3us @ 300K

Setup for experimental measurements Open collimator Closed collimator

Profiles in fast mode Beam current at nozzle: 1.1 nA Energy range: 3 ÷ 6 MeV Time of acquisition: 10s Open collimator Closed collimator All profiles are normalized to a uniformity flood acquired without collimator