Decay Spectroscopy at FAIR with AIDA presented by Tom Davinson on behalf of the AIDA collaboration (Edinburgh – Liverpool – STFC DL & RAL) Tom Davinson School of Physics & Astronomy The University of Edinburgh

Presentation Outline r-process Nuclear Physics Observables FAIR SuperFRS Decay Spectroscopy (DESPEC) Advanced Implantation Detector Array (AIDA)

r-process seed nuclei (A≥70) synthesis far from valley of stability equilibrium (n,  ) and ( ,n) reactions n-capture until binding energy becomes small wait for  decay to nuclei with higher binding energy Kratz et al., ApJ 403 (1993) 216

r-process: Nuclear physics observables ObservableEffect SnSn path T 1/2 abundance pattern timescale PnPn freezeout abundance pattern Primary nuclear physics observables from studying the decay spectroscopy (principally  and  -delayed neutron emission) of r-process nuclei

Cost –Approx €1000M –€650M central German government –€100M German regional funding –€250M from international partners Timescale –Feb German funds in budget –2007 project start –2016 phased start experiments –2018 completion NUSTAR Super FRS Future facility 100 m GSI today SIS 100/300 UNILAC ESR SIS 18 HESR RESR NESR FAIR: Facility for Antiproton and Ion Research

FAIR: SuperFRS layout courtesy of Martin Winkler, GSI Fast radioactive beams can be used to study r-process chemistry independent fast production measure several nuclei simultaneously measurements possible with low rates

FAIR: Production Rates from FAIR CDR, section 2 Predicted Lifetimes > 100ns

DESPEC: Implantation DSSD Concept SuperFRS, Low Energy Branch (LEB) Exotic nuclei – energies ~ 50 – 200MeV/u Implanted into multi-plane, highly segmented DSSD array Implant – decay correlations Multi-GeV DSSD implantation events Observe subsequent p, 2p,   p,  n … low energy (~MeV) decays Measure half lives, branching ratios, decay energies … Tag interesting events for gamma and neutron detector arrays

Implantation DSSD Configurations Two configurations proposed: a)8cm x 24cm “cocktail” mode many isotopes measured simultaneously b) 8cm x 8cm concentrate on particular isotope(s) high efficiency mode using: total absorption spectrometer moderated neutron detector array

Implantation – Decay Correlation DSSD strips identify where (x,y) and when (t 0 ) ions implanted Correlate with upstream detectors to identify implanted ion type Correlate with subsequent decay(s) at same position (x,y) at times t 1 (,t 2, …) Observation of a series of correlations enables determination of energy distribution and half-life of radioactive decay Require average time between implants at position (x,y) >> decay half-life depends on DSSD segmentation and implantation rate/profile Implantation profile  x ~  y ~ 2cm,  z ~ 1mm Implantation rate (8cm x 24cm) ~ 10kHz, ~ kHz per isotope (say) Longest half life to be observed ~ seconds Implies quasi-pixel dimensions ~ 0.5mm x 0.5mm

AIDA: DSSD Array Design 8cm x 8cm DSSDs common wafer design for 8cm x 24cm and 8cm x 8cm configurations 8cm x 24cm 3 adjacent wafers – horizontal strips series bonded 128 p+n junction strips, 128 n+n ohmic strips per wafer strip pitch 625  m wafer thickness 1mm  E, Veto and up to 6 intermediate planes 4096 channels (8cm x 24cm) overall package sizes (silicon, PCB, connectors, enclosure … ) ~ 10cm x 26cm x 4cm or ~ 10cm x 10cm x 4cm

ASIC Design Requirements Selectable gain MeV FSR Low noise keV FWHM energy measurement of implantation and decay events Selectable threshold< 0.25 – 10% FSR observe and measure low energy  detection efficiency Integral non-linearity 95% FSR spectrum analysis, calibration, threshold determination Autonomous overload detection & recovery ~  s observe and measure fast implantation – decay correlations Nominal signal processing time < 10  s observe and measure fast decay – decay correlations Receive (transmit) timestamp data correlate events with data from other detector systems Timing trigger for coincidences with other detector systems DAQ rate management, neutron ToF

Schematic of Prototype ASIC Functionality Note – ASIC will also evaluate use of digital signal processing Potential advantages decay – decay correlations to ~ 200ns pulse shape analysis ballistic deficit correction

Analogue inputs left edge Control/outputs right edge Power/bias top and bottom 16 channels per ASIC Prototypes delivered May 2009 MPW run 100 dies delivered Functional tests at STFC RAL OK Prototype AIDA ASIC: Top level design

AIDA ASIC simulation: example Optimum ASIC parameters identified by simulation

Prototype AIDA ASIC

Fixed high-energy (HE) event (610pC) followed by three ME events (15pC, 30pC, 45pC): the ASIC recovers autonomously from the overload of the L-ME channel and the second event is read correctly. Input signals (voltage step capacitive-coupled) Preamp buffered output (Low-Medium Energy Channel) “Range” signal High = high-energy channel active “Data Ready” signal 3: High Energy (HE) + ME

First value (constant) given by the High-Energy channel, second by the Medium-Energy channel. Input signals (voltage step capacitive-coupled) “Range” signal High = high-energy channel active “Data Ready” signal Analog output (peak-hold multiplexed output) 3: High Energy (HE) + ME

FEE Assembly Sequence

AIDA: status Systems integrated prototypes available - prototype tests in progress Production planned Q3/2010 Mezzanine: 4x 16 channel ASICs Cu cover EMI/RFI/light screen cooling FEE: 4x 16-bit ADC MUX readout (not visible) 8x octal 50MSPS 14-bit ADCs Xilinx Virtex 5 FPGA PowerPC 40x CPU core – Linux OS Gbit ethernet, clock, JTAG ports Power FEE width: 8cm Prototype – air cooling Production – recirculating coolant

ASIC Controls

Examples of prototype bench tests 1keV = 61  V 0.15mV rms ~ 2.5keV rms Si Test range ~ 20k channels

Prototype AIDA Enclosure - Design drawings (PDF) available

AIDA Enclosure Prototype mechanical design Based on 8cm x 8cm DSSSD evaluate prior to design for 24cm x 8cm DSSSD Compatible with RISING, TAS, 4  neutron detector 12x 8cm x 8cm DSSSDs 24x AIDA FEE cards 3072 channels Design complete Mechanical assembly in progress

AIDA

AIDA: outlook DSSSD with sub-contractor (MSL) ASIC submitted for wafer production run (AMS) – delivery January 2011 FEE mezzanine PCB – will be submitted for manufacture Nov 2010 – delivery January 2011 FEE PCB with sub-contractor - delivery January 2011 Mechanical design and infrastructure (HV, PSUs, cooling etc.) - STFC DL & University of Liverpool arranging manufacture/purchase Production complete hardware now available for integration/initial tests AIDA expected to be ready for commissioning/first experiments from 2011/Q3 Continuing development work in progress, e.g. MWD, integration with other detector systems

AIDA: Project Partners The University of Edinburgh (lead RO) Phil Woods et al. The University of Liverpool Rob Page et al. STFC DL & RAL John Simpson et al. Project Manager: Tom Davinson Further information: Technical Specification:

Acknowledgements My thanks to: STFC DL Patrick Coleman-Smith, Ian Lazarus, Simon Letts, Paul Morrall, Vic Pucknell, John Simpson & Jon Strachan STFC RAL Davide Braga, Mark Prydderch & Steve Thomas University of Liverpool Tuomas Grahn, Paul Nolan, Rob Page, Sami Ritta-Antila & Dave Seddon University of Edinburgh Zhong Liu, Phil Woods Prototype AIDA hardware tests at MARS Livius Trache et al., Cyclotron Institute, Texas A&M

Heavy Element Abundance: Solar System from B.S.Meyer, Ann. Rev. Astron. Astrophys. 32 (1994) 153 Si=10 6 r-process produces roughly one-half of all elements heavier than iron

Heavy element nucleosynthesis ProcessEnvironmentTimescaleEndpointSite s-process (n,  ) T 9 ~0.1  n >>    n ~1-1000a  n ~10 8 /cm 3 <10 6 a 209 BiAGB stars r-process (n,  ) T 9 ~1-2  n <<    n ~  s  n ~ /cm 3 <1sbeyond UType II supernovae? NS-NS mergers? p-processT 9 ~2-3~1sType II supernovae

r-process: What do observations tell us? from Cowan & Sneden, Nature 440 (2006) 1151 CS galactic halo star (intermediate population II) red giant ‘metal poor’ [Fe/H] = -3.0 Matches relative elemental solar abundance pattern common site/event type? applies to ‘metal poor’ and ‘metal rich’ stars – rapid evolution of old stars?

r-process: U/Th Cosmo-chronology from Cowan & Sneden, Nature 440 (2006) 1151 (13.8±4)Ga (14.1±2.5)Ga Cowan et al., ApJ 572 (2002) 861 Wanajo et al., ApJ 577 (2002) 853 long half-lives very similar mass r-process production only

r-process:  -delayed neutron emission Effect of  -delayed neutron emission: modification (smoothing) of final abundance pattern at freezeout S n <Q  increasing N → lower S n,higher Q  Kratz et al., ApJ 403 (1993) 216 before  -decay after  -decay

Proposed layout August 2006 (for illustrative purposes – way out of date!) courtesy of Martin Winkler, GSI FAIR: HISPEC/DESPEC

AIDA: ASIC schematic