New Development of Silicon Drift Detectors for the SIDDHARTA-2 experiment upgrade

1. New Development of Silicon Drift Detectors for the SIDDHARTA-2 experiment upgrade Carlo Fiorini, Riccardo Quaglia Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Milano, Italy. INFN, Sezione di Milano, Milano, Italy.

2. Outline • The Silicon Drift Detectors (SDDs) in SIDDHARTA-1 • New development of SDDs for SIDDHARTA-2 upgrade • Present and future work

3. SIDDHARTA SIlicon Drift Detector for Hadronic Atom Research by Timing Applications • LNF- INFN, Frascati, Italy • SMI- ÖAW, Vienna, Austria • IFIN – HH, Bucharest, Romania • Politecnico, Milano, Italy • MPE, Garching, Germany • PNSensors, Munich, Germany • RIKEN, Japan • Univ. Tokyo, Japan • Victoria Univ., Canada

4. Anodes Integration of the input FET on the detector to: - reduce of the parasitic capacitances of the connections between detector and electronics - improvement of the capacitive matching between detector gate capacitances (CdetCgate) • Features: • optimized geometry for X-ray Spectroscopy • low-noise, high-resolution Ionizing particle Rectifying electrodes • The electrons are collected by the small anode, • characterised by a low output capacitance, independent from the active area • The drift time can be used to retrieve the position of interaction Anode The Silicon Drift Detector (SDD)

5. SDD board detector +readout module readout board with ASIC 3 SDD (1cm2 each) with on-chip JFET and feedback cap

6. Silicon Drift Detector - SDD 1Chip : 1 cm2

7. 1 cm2 x 144 SDDs

8. What have we learned about the SDDs of SIDDHARTA-1? • SDDs are a valuable X-ray spectroscopy detector for exotic atoms measurements • but: • latch-up of JFET integrated in the SDD during beam injection • very fine tuning of bias of individual SDD was required • dead-area of the detection module may be further minimized • low-energy detection (<3keV) limited because of technical issues (electronics, thresholds, pick-up noise, …). • …but no intrinsic SDD limitations (>200eV) • ….. • (our friends in Frascati may have learned much more than us….)

9. The SIDDHARTA-2 setup upgrade • new target design • new SDD arrangement • vacuum chamber • more cooling power • improved trigger scheme • shielding and anti-coincidence (veto) • New SDDs – Milano – 200 cm2 9

10. New development of SDDs by Politecnico & FBK • Started in 2011 within a project supported by ESA • Considered very suitable for the upgrade of the Siddharta-2 apparatus, with preliminary evaluation on prototypes in 2012/2013 • Key features of the proposed technological approach: • process of SDD detectors WITHOUT JFET integrated on the SDD itself (as used on current SIDDHARTA apparatus). • advantages: • - simplicity • - much lower production costs (much less techn. steps) • - faster production times (3-4 months vs. one year) • - much lower dependence of settings/performances on bias voltages than with the present detectors • - less sensitivity to latch-up during beam injection • SDD readout based on a new charge preamplifier “Cube” (recently developed at Politecnico di Milano): • - allows high performances in X-ray spectroscopy still using ‘conventional’ SDD technology (W/O integrated JFET)

11. Present layouts of SDDs developed in the Polimi-FBK collaboration Array: 9 SDDs (8 x 8 mm2 each) 8 x 8 mm2 single SDD 26mm 12 x 12 mm single SDD • FBK production: • 4’’ wafer • 6’’ wafer upgrade just finished

12. Front-end readout strategy radiation entrance window • JFET integrated on the SDD SDD • lowest total anode capacitance • limited JFET performances (gm, 1/f) • sophisticated SDD+JFET technology Now in Siddharta cooler CUBE • external CUBE preamplifier • (MOSFET input transistor) Proposed for Siddharta-2 • larger total anode capacitance • better FET performances • standard SDD technology

13. CUBE: A full CMOS preamplifier can replace the single JFET+Cf+reset <1mm3 Leakage and photons reset 30 ns 55Fe signal (SDD) CUBE SDD

14. Best performances of new SDD technology and CUBE preamplifier 55Fe spectrum 123.0 eV FWHM • SDD characteristics: • Area = 10mm2 • T= -40°C (ENC= 3.7 e- rms) 1.0 ms shaping time (optimum) 250ns shaping time 126.4eV FWHM best resolution ever obtained with a SDD (even with integrated JFET) at this short shaping time (ENC= 5.0 e- rms)

15. Stability of the X-ray spectroscopy spectrum with SDD bias

16. Set-up for testing SDDs: Vacuum Chamber Cryostat cooling down to 50 K Vacuum Chamber Connector to output Special 55Fe source for vacuum application mounted here Connector for bias and output SDD: 8x8 mm2

17. Stability tests (in Milano, other tests on-going in Frascati) 72 hours FWHM= 126.8eV square SDD: 64 mm2 meas. time: 72 hours T= 100 K Rate: 1.1 kcps Vacuum chamber set-up.

18. Monolithic array of 3x3 SDDs: an ideal detector for Siddharta-2 upgrade 26mm • 55Fe spectra • T=-20°C 1mm dead space on each side: 85% active area 9 holes for bondings CUBE preamplifier Detector module connector Ceramic carrier

19. Upgrade of Siddharta-2 spectrometer based on: • new SDDs development • CUBE and ASICs readout • low dead-area detection module design • Few numbers: • 200cm2 of SDDs arrays • 36 SDDs monolithic arrays • 324 readout channels (drawings courtesy of SMI-ÖAW team)

20. ASIC to readout the SDD arrays • 27 channels • Shaper filter Semi-Gaussian 7th order complex poles. • Peaking Time 2, 3, 4 or 6µs • 3 Gain: 10k, 20k, 30k e-; • SPI 160 bits; • Multiplexer 27 to 1 • MUX clock 10 MHz • Digital transfer standard LVDS ASIC From/To preamplifiers (Input signals, Reset) DAQ

21. Present and future work • Experimentation of single SDD (8x8mm2) almost completed • (resolution, stability, linearity….) • Experimentation of 3x3 SDDs array on the way: • mounting and bonding optimization, yield • test at low temperatures (100K) • qualification as for the single SDD (Milano, Frascati) • Design of a readout ASIC for the new SDD arrays • Revision/design of the DAQ system • Revision of components (detector layout, hybrids, module, …) for the SIDDHARTA-2 upgrade and production (depending on financing and support to man-power)

22. The new SDD development collaboration Politecnico di Milano and INFN, Milano, Italy C. Fiorini, R. Quaglia, P. Busca, R. Peloso, M. Occhipinti, L. Bombelli, A.Geraci Fondazione Bruno Kessler - FBK, Trento, Italy P. Bellutti, M. Boscardin, F. Ficorella, G. Giacomini, A. Picciotto, C. Piemonte, N. Zorzi LNF - INFN, Frascati, Italy M. Bazzi, M. Iliescu, F. Sirghi, C. Curceanu, ….