The SpecMAT project: An array of gamma-ray detectors around an active gas target J. A. Swartz (KU Leuven- IKS) ATTPC workshop Michigan State University 19/05/2015
Contents 1. The SpecMAT Project 2. Scintillators vs HPGe detectors 3. The SiPM approach 4. Next steps Co-authors: KU Leuven: R.Raabe, H. De Witte University of York: D. Jenkins, P. Joshi, N.S. Bondili
The SpecMAT project: To investigate exotic nuclei, specifically neutron-rich around Z = 28, e.g. 68, 70Ni; 78, 80Zn neutron-deficient around Z = 82, e.g. 184Hg, 188Pb, 196Po stable nuclei observed nuclei unknown nuclei (predicted) 82 Pb 208 50 126 78 28 20 50 8 20 28 28 1. The SpecMAT project Ni 82
The SpecMAT project: To investigate exotic nuclei, specifically neutron-rich around Z = 28, e.g. 68, 70Ni; 78, 80Zn neutron-deficient around Z = 82, e.g. 184Hg, 188Pb, 196Po stable nuclei observed nuclei unknown nuclei (predicted) 82 Pb 208 50 126 78 28 20 50 8 20 28 28 1. The SpecMAT project Ni 82 Ni Most exotic doubly-magic nucleus which may be reached in foreseeable future 78
The SpecMAT project: To investigate exotic nuclei, specifically neutron-rich around Z = 28, e.g. 68, 70Ni; 78, 80Zn, (d,p); (d,3he) neutron-deficient around Z = 82, e.g. 184Hg, 188Pb, 196Po, (d,p); (p,d) stable nuclei observed nuclei unknown nuclei (predicted) 82 Pb 208 50 126 78 28 20 50 8 20 28 28 1. The SpecMAT project Ni 82 Direct transfer reactions possible in this region with 5 10 MeV/u beams from HIE-ISOLDE - CERN
ACTAR TPC: Based at GANIL-Caen, to be used at HIE-ISOLDE, SPES-Legnaro Demonstrator (2048 channels) operational Final detector: 16 384 channels in 2016 magnetic field Each channel corresponds to one 2 mm * 2 mm pad => 256 mm * 256 mm segmented detection plane Will use the existing GET electronic system With SpecMAT o Possibility of magnetic field in direction parallel to beam particles to confine emitted particles, thus providing larger dynamic range. o Would use UK Solenoid (right) 1. The SpecMAT project electric field
ACTAR TPC: Based at GANIL-Caen, to be used at HIE-ISOLDE, SPES-Legnaro Demonstrator (2048 channels) operational Final detector: 16 384 channels in 2016 Each channel corresponds to one 2 mm * 2 mm pad => 256 mm * 256 mm segmented detection plane Will use the existing GET electronic system, as will ancillary detectors? Ancillary detectors: DSSSD array for particle detection Gamma-ray detectors SpecMAT 1. The SpecMAT project
Two different options for SpecMAT gamma-ray detector array: Scintillation detectors (either LaBr3(Ce) or CeBr3) Broad-energy high-purity Germanium (BEGe) detectors 2. Scintillators vs HPGe detectors
F. Quarati et al., NIM A 729 (2013) 596-604 2. Scintillators vs HPGe detectors
LaBr3(Ce) scintillators Resolution 2.7-3.3% for 662 kev gamma rays from Cs Density 5.07 g/cm3 Internal contamination problems due to Lanthanum Patented by Saint Gobain (though also sold through Canberra, Ortec..) Price ~ 9 000 EUR per scintillator for 1.5"*1.5" model CeBr3 scintillators Resolution 3.8-4.0% for 662 kev gamma rays from Cs Density 5.19 g/cm3 No internal background (unless you have 227Ac contamination) Produced by Scionix Holland, RMD, Kinheng Crystal.. Price ~ 4 500 EUR per scintillator for 1.5"*1.5" model 2. Scintillators vs HPGe detectors
Alternative solution: BEGe detectors from Canberra Diameter = 90 mm Thickness = 30 mm Figure from Canberra website: http://www.canberra.com/products/detectors 2. Scintillators vs HPGe detectors
Geant4 simulations Scintillators Reaction Ni(d,p)79Ni at 10 MeV/u, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides, used ACTARsim code From 100 000 ACTAR events 2"*2 "scintillators: 6618 gamma rays observed 6.62% efficiency Green layer 1 mm of Si 2. Scintillators vs HPGe detectors
Geant4 simulations Comparison Reaction 78Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 100 000 ACTAR events (normalised to 25 000 in spectrum left) Counts / 100 kev 45 CeBr3 detectors (51 mm * 51 mm det. dimensions) 6618 gamma rays 6.6% efficiency 25 000 ACTAR events 12 `ProFile' Ge detectors (from ORTEC) (82 mm * 50 mm det. dimensions) 1305 gamma rays => 5.2% efficiency Energy [MeV] 2. Scintillators vs HPGe detectors
o o Problem with scintillators + PMTs & HPGe detectors: Detectors need to work in high B-field... 3. The SiPM approach
Problem with scintillators + PMTs & HPGe detectors: o Detectors need to work in high B-field... o Solution: replace PMTs with Silicon Photomultipliers (SiPMs) to read out scintillator crystals. o http://sensl.com/products/silicon-photomultipliers 3. The SiPM approach
LaBr3(Ce) tested at University of York Industrial applications lab Coupled 51x51x51 mm LaBr3 to 8x8 array of 6x6 mm SiPMs Optimized Voltage (29 to 30 V) and shaping time (0.5 μs) SensL PCB 3. The SiPM approach LaBr3 crystal with SiPMs Crystal on PCB
SiPM data, J.A. Swartz, D. Jenkins, P. Joshi and N.S. Bondili 2 2" cubic crystal data obtained with SiPM and LaBr3 (top) and PM tube + LaBr3, CeBr3, NaI (bottom, F. Quarati et al., NIM A 729 (2013) 596-604) 3. The SiPM approach
SiPM data, J.A. Swartz, D. Jenkins, P. Joshi and N.S. Bondili 3. The SiPM approach Good linearity of energy to signal
SiPM data, J.A. Swartz, D. Jenkins, P. Joshi and N.S. Bondili 3. The SiPM approach Good linearity of energy to signal Resolution, from fit FWHM = 4.0%, after non-linearity correction FWHM = 4.2%
SiPM data, J.A. Swartz, D. Jenkins, P. Joshi and N.S. Bondili SiPM results approach what is attainable with scintillators coupled to conventional PMTs 3. The SiPM approach Good linearity of energy to signal Resolution, from fit FWHM = 4.0%, after non-linearity correction FWHM = 4.2%
Summary Tests (ideal conditions): LaBr3(Ce) provides around 3% with PMTs CeBr3 provides 4% with PMTs With SiPMs LaBr3:Ce can provide ~4% with SiPMs CeBr3 can provide ~5% with SiPMs LaBr3 contamination from Lanthanum, not present with CeBr 3 SiPMs can operate in a high magnetic field, PMTs cannot 3. The SiPM approach
Prototypes to be tested with chamber at KU Leuven, using conventional PMTs o 1.5" 1.5" o 2" 2" 4. Next steps
Prototypes to be tested with chamber at KU Leuven 4. Next steps
Prototypes to be tested: 1.5"*1.5" LaBr3(Ce) and CeBr3 cylindrical detectors, 2"*2" CeBr3 cylindrical detector, 1.5"*1.5" LaBr3(Ce) and CeBr3 cubic detectors with SiPMs Tests to be performed with various electronic systems Final array purchase to begin by Christmas 2015 4. Next steps
Hiring two PhD students for SpecMAT from September 2015. Contact raabe@kuleuven.be
Acknowledgement: The research leading to these results has received funding from the European Commission s Seventh Framework Programme (FP7/2007-2013) under the grant agreement SpecMAT (project no. 617156).
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