FAZIA Collaboration recent advances and perspectives RD Phase

FAZIA Collaboration: recent advances and perspectives R&D Phase I of FAZIA and optimizing Z and A identification by means of Pulse Shape in Silicon: • Basic detection module: Si-Si-Cs. I (non-standard) • Charge and current preamplifier (PACI) • Fully digital electronics for Energy, Pulse Shape and Timing has been developed • Pulse Shape and Silicon material: importance of controlling channeling and doping uniformity • First prototypes tested in-beam • Pulse Shape: what are thresholds (E, Z and A)? • Pulse Shape + To. F (SPIRAL 2 PP + …. ) • Pulse Shape for low energy hydrogen and helium isotopes In this talk: FAZIA Phase II dedicated to implement results of Phase I: • Prototype Array (a small scale version of FAZIA) • New Front End Electronics Not discussed, only reminded Discussed Briefly addressed and commented G. Poggi – EURORIB 08 – June 2008

The FAZIA Initiative The FAZIA (Four Pi Z and A Identification Array) initiative was formalized in 2006. Members are from France, Italy, Poland, Spain, Rumania (+Canada, India and US). The goal of the present Phase I: studying and testing new solutions, checking if possible to make a step forward toward the “ideal” detector array for Dynamics and Thermodynamics of heavy-ion collisions at Fermi energies and below http: //fazia. in 2 p 3. fr FAZIA PHASE I: Working Groups 1. Modeling current signals and Pulse Shape Analysis in Silicon (L. Bardelli) 2. Physics cases (G. Verde) 3. Front End Electronics (P. Edelbruck) ΔE 1 4. Acquisition (A. Ordine) 5. Cs. I(Tl) crystals (M. Parlog) 6. Single Chip Telescope (G. P. ) Si ΔE 2 Si Cs. I(Tl) H. I. ? 7. Design, Detector, Integration and Calibration (M. Bruno) 8. Web site (O. Lopez) 300μm 500 / 700μm 30 -100 mm G. Poggi – EURORIB 08 – June 2008

Beyond E-E: Z and A Identification with Pulse Shape Why Pulse Shape in Silicon is possible? • Stopped particles with the same energy and different Z (and A) show charge/current signals having unlike time evolution because ranges and plasma erosion times differ • Better identification for reverse-mount Silicon Energy vs rise-time of charge signals permits good Z identification of stopped particles (further identification criteria under study) A threshold exists for Z identification, for small particle penetration (a few tens of μm) B C N O Evidences exist that isotope separation (A identification) is possible above a certain penetration. First fully digital implementation of PSA in Silicon : L. Bardelli et al: NP A 746 (2004) 272 G. Poggi – EURORIB 08 – June 2008

Channeling and doping non -uniformity in Si for PSA IEEE TNS 47 (2000) 756 ) 82 Se @ 408 Me. V ~100 mm 2 Silicon Current [a. u] Only very small scale implementation of highquality PSA are reported in the literature (see Mutterer et al Elastic scattering on Au ns G. Poggi – EURORIB 08 – June 2008

Channeling and doping non -uniformity in Si for PSA IEEE TNS 47 (2000) 756 ) Early FAZIA tests of our DPSA in Silicon with mono-energetic heavy-ions showed fluctuations in current and charge signal shape (also somewhat irreproducible) Basing on an older work (G. P. et al. NIM B 119 (1996) 375) on channeling effects on stopped h. i. , we suspected that channeling (and Silicon doping non-uniformity) was originating these instabilities. Could this also explain overall irreproducibility of PSA quality observed in the past? 82 Se Current [a. u] Only very small scale implementation of highquality PSA are reported in the literature (see Mutterer et al @ 408 Me. V Elastic scattering on Au ns The key experiment: collimated Silicon detectors mounted on a remote-controlled precision goniometer. Signal behavior as a function of the impinging ion direction with respect to crystal axes. Both <100> and <111> silicon detectors have been studied G. Poggi – EURORIB 08 – June 2008

Signal Risetime and Channeling in <100> and <111> Silicon “Channeled” Our findings for “Channeled” or “random-entering” stopped ions Channeled ions: strongly fluctuating rise-time due to… enhanced variations of range and plasma erosion time for directions close to crystal channels, which are basically… 80 Se @ 408 Me. V “Channeled” ns G. Poggi – EURORIB 08 – June 2008

Signal Risetime and Channeling in <100> and <111> Silicon Our findings for “Channeled” or “random-entering” stopped ions “Random” Channeled ions: strongly fluctuating rise-time due to… enhanced variations of range and plasma erosion time for directions close to crystal channels, which are basically… 80 Se @ 408 Me. V 80 Se “Channeled” @ 408 Me. V “Random” … absent for random directions For <111> Silicon: typically 7° off-axis L. Bardelli et al; submitted to NIMA <111> Si Fluctuation increases Risetime-fluctuations vs gonio-angles ns ns If detectors subtend ~1° and are mounted in the usual way, most ions may experience abnormal fluctuations, given the large channeling probability (ψ½ = 0. 5°-1°) Channeling in Silicon is observed for front and rear injection G. Poggi – EURORIB 08 – June 2008

Signal Risetime and Channeling in <100> and <111> Silicon 80 Se USE PURPOSELY ORIENTED SILICON DETECTORS for ALWAYS MAINTAINING RANDOM INCIDENCE! Current [a. u] The mandatory recipe for good Pulse Shape Analysis: @ 408 Me. V <100> Silicon “Channeled” We have ordered indeed special-cut n. TD wafers Irreproducibility: minor geometry variations of the setup change the fraction of channeled ions Unfortunately this does not explain everything… The Silicon doping uniformity must also be controlled up to an unprecedented level This information is basically not available from (detector/wafer) manufacturers “Random” ns ns L. Bardelli et al: submitted to NIMA G. Poggi – EURORIB 08 – June 2008

Resistivity measurements (doping uniformity) in Silicon A newly developed procedure to map Silicon resistivity, based on Transient Current Technique has been systematically applied to our detectors Narrow UV laser pulse (ns) Fixed impact point Si detector Various bias voltage R Over depletion Full bias Slightly under-bias Reverse-mount Silicon det. Various applied voltages: from under- to over bias T_rise G. Poggi – EURORIB 08 – June 2008

Resistivity measurements (doping uniformity) in Silicon A newly developed procedure to map Silicon resistivity, based on Transient Current Technique has been systematically applied to our detectors A typical detector: ~9% non-uniformity with striations (mm-1 spatial frequency) Narrow UV laser pulse (ns) Fixed impact point Si detector Various bias voltage R Over depletion Full bias Slightly under-bias Reverse-mount Silicon det. Various applied voltages: from under- to over bias T_rise G. Poggi – EURORIB 08 – June 2008

Resistivity measurements (doping uniformity) in Silicon A newly developed procedure to map Silicon resistivity, based on Transient Current Technique has been systematically applied to our detectors Narrow UV laser pulse (ns) Fixed impact point Si detector R Various bias voltage Over depletion Reverse-mount Silicon det. Various applied voltages: from under- to over bias A non typical, very good detector: ~1% nonuniformity with undetectable T_rise striations Full bias Memento: good resistivity Slightly under-bias uniformity good uniformity of electric field position independence of timing G. Poggi – EURORIB 08 – June 2008

PSA test run with full control of channeling and resistivity 32 S + 27 Al @ 474 Me. V (LNL, December 2007) Si-Si, Si-Cs. I and “Single Chip Tel” have been used. All Silicons were characterized for uniformity, were un-collimated and have the “FAZIA” dimensions(400 mm 2) PACI preamps A fully digital FEE for charge and current PSA has been developed (Orsay+Florence) for Phase I Channeling control for the experiment: Detectors made of random-cut Silicon were not yet available All detectors are cut 0° off <111> axis Channeling--random control obtained by proper 7° detector tilting (simple mechanical adjustment permits to switch from unwanted channeling to desired “random” orientations) Channeled ions Random entering ions Quasi-random entering ions Wrong detector mounting causes some residual planar channeling G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007) Channel or not to channel? DIGITAL PULSE SHAPE on 500μ Silicon +27 Al @ 474 Me. V O N C B Be Normally impinging ions Ne Na 500 μ F Are channeling Pulser effects really important? Full scale: ~1. 5 Ge. V 300 μ 32 S Very uniform 500μm Silicon Standard mounting, i. e. perpendicular ion incidence is expected to induce channeling Satisfactory Z identification over the full examined range G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007) Channel or not to channel? DIGITAL PULSE SHAPE on 500μ Silicon +27 Al @ 474 Me. V O Random impinging ions Ne Na N 500 μ F Yes, they are! Channeling was Pulser spoiling mass identification Full scale: ~1. 5 Ge. V 300 μ 32 S Very uniform 500μm Silicon C B Be Channeling was partly spoiling overall identification Random: 7° tilt angle Mass identification clearly shows up! G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007) Channel or not to channel? 32 S +27 Al DIGITAL PULSE SHAPE on 500μ Silicon @ 474 Me. V Full scale: ~ 4 Ge. V S P Si Al Normally impinging ions Cl Ar K 500 μ Mg Na Ne F N B Be Very uniform 500μm Silicon O Standard mounting, i. e. perpendicular ion incidence C Satisfactory Z identification over the full examined range Unity counts removed Note the very high energy range G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007) Channel or not to channel? 32 S +27 Al DIGITAL PULSE SHAPE on 500μ Silicon @ 474 Me. V Full scale: ~ 4 Ge. V S P Si Al Random impinging ions Cl Ar K 500 μ Mg Na Ne F N B Be Very uniform 500μm Silicon O Channeling was partly spoiling identification C “Random” mounting Unity counts removed G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007): doping uniformity DIGITAL PULSE SHAPE on 500μm and 300μm Silicons with similar field and different doping non-uniformities 140 V on 300μm 9. 4% non-uniformity S Cl? 300μm: ~ 4 Ge. V full scale Ar? 500μm: ~ 4 Ge. V full scale 300 μ O N BC Be P Si Al Mg Na Ne F Quasi-random, but non-uniform Silicon shows reasonable Z resolution 250 V on 500μm 1% non-uniformity B Be N C F Cl Ar Quasi-random, very uniform Silicon shows clean Z and partial A resolution K Ca 500 μ O Al Mg Na Ne Si P S G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007): doping uniformity Al DIGITAL PULSE SHAPE on 500μm and 300μm Silicons with similar field and different doping non-uniformities 140 V on 300μm Mg Na 9. 4% non-uniformity Ne PS Cl? Si Ar? Al. F Mg O Na Ne NO F N C B 140 V on 300μm Be C 300μm: ~ 4 Ge. V full scale 300 μ 500μm: ~ 4 Ge. V full scale 9. 4% non-uniformity Quasi-random, but non-uniform Silicon shows reasonable Z resolution Al Mg 250 V on 500μm Na 1% non-uniformity O F O N C B Be F Al Mg Na Ne Si P S Cl Ar Quasi-random, very uniform Silicon shows clean Z and partial A resolution K Ca N C 250 V on 500μm 1% non-uniformity 500 μ Ne G. Poggi – EURORIB 08 – June 2008

FAZIA Phase I: Digital Pulse Shape on Silicon Preliminary conclusions: with uniformity-controlled and “random”-oriented Silicon detectors, Digital PSA developed in FAZIA permits unity charge resolution at least up to Z ~ 30 (probably >50), with energy thresholds of about 3 Me. V/n for C and 4 Me. V/n for Ne (about 30 -40 μm of Silicon) DPSA gives mass resolution for Z<1520 (also based on short-run results with 58, 60 Ni) particles, with ranges > 100μm (? ) of Silicon To. F might significantly extend this mass resolution Frankly, we are not unhappy about these preliminary results… 60 Ni 58 Ni G. Poggi – EURORIB 08 – June 2008

FAZIA Phase I: next steps Best algorithms for DPSA are under study within FAZIA WG 1 (S. Barlini et al: in 3 rd vs 2 nd moment of current signals preparation) Adding To. F to current or charge risetime for extending mass resolution of low energy stopped particles Exp+Sim Trying to get To. F even with nonoptimal time structure of the pulsed beam (supported by Spiral 2 PP) Addressing Digital Pulse Shape for Silicon strip and Z = 1, 2 ions (supported by Spiral 2 PP) Future experiments: LNL, LNS, GANIL… Y axis: measured energy X axis: measured rise-time + simulated To. F over 1. 1 m and 0. 5 ns FWHM (smoothly merged) G. Poggi – EURORIB 08 – June 2008

FAZIA R&D Phase II (and Phase III) Phase II (from 2008 till 2012): • • C 2 Prototype Array (20 -30 modules) to couple with existing arrays and do Physics out of it • Implement the solutions devised and tested on Phase I • adopt electronic and mechanical solutions as close as possible to the final 4π configuration (e. g. neutron detection feasibility and transportability) C 1 C 3 C 4 ~104 telescopes A possible final FAZIA Array (JM Gautier-LPC) Phase III (from 2012 on): • Build a Demonstrator, covering a significant fraction of 4π, e. g C 2+C 1 x 8 G. Poggi – EURORIB 08 – June 2008

FAZIA R&D Phase II: the FEE structure under vacuum to simplify connections (the very issue under study: power removal) Bidirectional fast (2. 2 Gb/s) fiber optics guarantees synchronous trigger info transmission and transfer of samples (data). The last level provides trigger construction / validation / event labeling + sample dispatching to DAQ Fast FPGA-based elaboration and protocol management Trigger decision (400 ns) Data transmission Trigger to PC farm validation and event Samples labeling Trigger Box Trigger info . . 64. . Trigger and data collector + dispatcher Trigger info and samples 2. 2 Gb/s Trigger validation and slow control 2. 2 Gb/s DAQ Ethernet Trigger/samples separation and trigger elaboration Air Vacuum First Level FEE Unit. . 16. . Fast and slow Energy shaping First Level FEE First Local digital trigger generation (100 Level FEE Unit ns)+ second level decision (over in Unit 2 -3 μs) + data sending (asynchronous). . 16. . 640. . 16. . G. Poggi – EURORIB 08 – June 2008

The FAZIA organization FAZIA Working Groups 1. Modeling current signals and Pulse Shape Analysis (L. Bardelli) FAZIA Project Management Board: 2. Physics cases (G. Verde) B. Borderie, R. Borcea, R. Bougault, A. Chbihi, F. Gramegna, T. Kozik, I. Martel Bravo, E. Rosato, G. P. and R. Roy 3. Front End Electronics (P. Edelbruck) Sc. Coordinators: G. P. and R. Bougault Tech. Coordinator: P. Edelbruck A dedicated Discussion Group is studying the Physics requirements for the Trigger (M. F. Rivet and A. Olmi) to implement with our electronic engineers 4. Acquisition (A. Ordine) 5. Cs. I(Tl) crystals (M. Parlog) 6. Single Chip Telescope (G. P. ) 7. Design, Detector, Integration and Calibration (M. Bruno) 8. Web site (O. Lopez) Two more slides on “synergies” G. Poggi – EURORIB 08 – June 2008

Synergies in instrumentation Questions fitting very well with our Topic Is channeling an issue only for PSA-based identification? How about channeling and more standard identification approaches? Elastic scattering in @ 30 Me. V/n 93 Nb+116 Sn E Significant effects are expected in E-E: channeling may change E, as many of us have seen when punching-through elastic scattering is measured This effect is less clearly appreciated in other cases, but still present E G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007) +27 Al @ 474 Me. V Try a little, proper detector tilting … Na Ne Digital E-E 300 -500μ Silicon (reverse field) Full scale E: ~4 Ge. V Full scale E: ~1. 5 Ge. V Normally impinging ions F 300 μ N C B 500 μ O Telescope mounted for standard normal incidence Be Why so-so resolution? Li Unity counts removed Never happened to you? G. Poggi – EURORIB 08 – June 2008

32 S + 27 Al @ 474 Me. V (December 2007) Beneficial effects of random incidence for standard E-E identification 32 S Digital E-E 300 -500μ Silicon (reverse mount) +27 Al @ 474 Me. V … say channeling “goodbye” Full scale E: ~4 Ge. V Full scale E: ~1. 5 Ge. V Na Ne Random impinging ions F C B Be Li 500 μ N We believe that one should keep this result in mind for any future E(Si)-E implementation. Do not overlook the old recommendation Telescope mounted of 7° off-axis cut and double checkfor 7° incidence what you buy. (Quasi-random 300 μ O configuration) Thanks to the audience Unity counts removed G. Poggi – EURORIB 08 – June 2008