Design study for a 4  ancillary detector for light charged particles to be used together with  -ray arrays in fusion-evaporation and direct reactions C.M. PetracheTrento, January 16-20, 2006 C.M. Petrache, D. Mengoni, M. Fantuzi – Camerino G. Ambrosi, E. Fiandrini – Perugia G. Prete, A. Gadea, G. De Angelis, R. Ponchia, G. Bassato – Legnaro E. Farnea, F. Recchia – Padova M. Boscardin, C. Piemonte, M. Novella, N. Zorzi - Trento

Physics Case Study of the structure of exotic nuclei using secondary radioactive beams using Fusion-evaporation reactions in inverse kinematics to measure Energy and Angle of light charged particles (p,  ) with Ancillary detectors coupled with gamma arrays using Direct reactions in inverse kinematics to measure Energy and Angle of the recoiling light particle

AGATA Ref.: Agata Proposal.

TRACE Fusion-evaporation -> different from TIARA & MUST (transparent, high granularity forward, low-energy threshold backward) Direct reactions -> similar characteristics like TIARA & MUST

AGATA + reaction chamber  = 40 cm Large space for ancillary detectors & electronics

Monte Carlo simulations with GEANT4 for the barrel geometry

Main requirements of our detector for light charged particles Detector specifications: –Efficiency –Geometry –Position resolution –Energy resolution –Time resolution –Energy range –∆E-E technique & PSA Electronics –ASIC’s –DSS

Main Requirements ➢ High detection efficiency: it has to cover as much as possible the solid angle, with a high granularity in order to minimize multiple hits probability. ➢ Transparent to gamma rays for the coupling with a gamma spectrometer. ➢ Fine discrimination among the various particles: protons, alphas and heavier ions. ➢ Good position resolution: for Doppler correction and good energy resolution. ➢ Good energy resolution: for detailed spectroscopy. ➢ Good time resolution: for TOF discrimination of light ions. ➢ Wide energy range: measurement of various reactions. ➢ Pulse shape analysis: fast DSS to achieve very low thresholds.

Detector Specifications Detector: made of Silicon to minimize the absorption of gamma rays, thin junction window (0.1  m). Geometries: ∆E: Si-pad det. <150  m thick, pad 2x2 mm 2, strip 2 mm E: Si-pad det. >1.5 mm thick, pad 2x2 mm 2, strip 2 mm Dimensions: 40 x 80 mm 2 Angular Resolution: 1°, 1-2 mm at 15 cm Energy resolution: <50 keV for 5 MeV  -particles Wide energy range: 200 keV-20 MeV for p, 80 MeV for  Time Resolution: 500 ps for A=8 & 2 MeV/u Pulse shape analysis: 2 GHz, >10 bits Coupling: AC

Coupling with AGATA demonstrator

Coupling with AGATA 2 

Lateral faces 8  E-E modules with orthogonal Si-strip

Forward 4  E-E modules with Si-pad Backward 4  E-E modules with Si-strip

EUCLIDES : EdE Si-ball for charge particle detection and identification. ΔE ~ 130 um E ~1000 um TRACE : EdE Si-Pad for charge particle detection and identification. ΔE ~ 150 um E ~1500 um Transparency

Goal: checking the feasibility of tracking with the first cluster prototype under (future) AGATA working conditions. First AGATA Experiment (Sept IKP KOLN)

Ancillary device: DSSD 32 rings 64 sectors Ge detector: first AGATA symmetric cluster (3 detectors) Experimental apparatus

FWHM = 300 keV 48 Ti*(d,p) 49 Ti* 48 Ti(d,d) 48 Ti* Evidence For Various Reactions

in out MAIN FEATURES: 1.Cross section produced with DWBA and loaded in the C code. 2.Energy lost of the beam in the target before interaction 3.Proton energetic and directional straggling 4.Recoil energetic straggling after interaction 5.Gammas loaded from an input file in the generator Event generator: (d,p) reactions in inverse kinematics Ref.:DWBA. Simulated System

FHWM 33 keV (cluster) 15.6 keV (single) 7 keV 4.3 keV (single) Simulated Doppler correction

Electronics Dynamic range for Light Charged Particles MeV Si = 56x x10 6 e - = 9 fC – 1 pC Ranges in silicon for protons: 15 MeV1.5 mm 20 MeV2.5 mm Ranges in silicon for protons: 15 MeV1.5 mm 20 MeV2.5 mm Ranges in silicon for alphas: 60 MeV1.5 mm 80 MeV2.5 mm Ranges in silicon for alphas: 60 MeV1.5 mm 80 MeV2.5 mm Number of channels: ~ 8000 Pulse shape analysis: DSS 2 GHz, 10 bits Multiplexer based system for reducing the number of ADS and feed-through by a factor of ~ 100 R&D for ASIC with PSA

Electronics ASIC read-out chips: to reduce at minimum the very limited space available around the target, the large number of electronic channels associated with the segmented detectors. Tests of Si-pad detectors coupled via various boards to different ASIC chips are under way at Legnaro and Camerino. ChipBoard VA32C2-TA32CGVA_TA_HPD2_H7546 VA32_HDR_11-TA32 VA_TA_HPD2 VATAGP3 – 128 channels, sparse read-out, range 18 fC System Test VADAQ

Tests have been performed on both Micron detectors, on several channels with either the ASIC or standard electronics, leading to encouraging results. ASIC electronics (VA32_HDR11 chip  -source: 241 Am source in air at 1 cm FWHM ~ MeV (9.1%) Standard electronics  -source: 241 Am source FWHM ~ MeV (1.3%)

1 mm thick Sintef detector + ASIC (VA32C2-TA32CG) γ -Sources: 241 Am, 57 Co energy resolution: ~ 6 60 keV (10%)

strip1 strip2 PAD1 PAD3 PAD2 STRIP: 64 strips/side; strips orthogonal on the two sides strip pitch 500 µm Two different strip width: 300 µm (STRIP1) 200µm (STRIP2). PAD1=AC, 6x5 pads, 4x4 mm 2 PAD2=AC, 8x32 pads, 1x1 mm 2 PAD3=DC, 8x8 pads, 2x2 mm 2 New Si-pad Detectors from IRST - Trento Thickness 1.5 mm Thin junction window (up to 100÷200 nm) High resistivity (>30 kΩ · cm) Bias voltage: 200÷300 V (multi guard rings) One single metal layer Near edge bonding contacts

PAD1= AC coupled 6x5 pads 4x4 mm 2 Signal extracted on the opposite sides to reduce strip length. 120  m 500  m 140  m

Tests of Si-Pad Detectors and Read-out ASIC Electronics Rear and front side of the adapter board on which the SINTEF Si-pad detector has been bonded. The adapter board can be inserted on the VATA- HPD2-H7546 read-out board, endowed of a suitable pin mask. SINTEF MICRON

Results on Si-pad Detectors and Read-out Electronics The Si-pad detectors were bonded to the electronic read-out board and characterized in the clean room of the INFN Sezione di Perugia. Detailed measurements of Si-pad detectors of various geometries with either classical or ASIC read-out electronics were performed at the University of Camerino, Legnaro National Laboratory (LNL) and at INFN Sezione di Perugia. The leakage current as a function of the bias voltage in 1 mm thick detectors. The red lines represent two different measurements on the same detector. The capacitance as a function of the bias voltage in 1 mm thick detectors. The detector is fully depleted at around 150 V.

Equivalent noise charge (ENC) of the VA32_HDR11 chip, in units of electron charge, as a function of the input capacitance has been measured. A linear fit of the experimental data is also shown, which is given by the relation: The linearity of VA32C2 chip extends up to 220 keV, and the ENC curve is described by the relation: The statistical fluctuation for 60 keV photons in Silicon is 130 e -, which gives an energy resolution of 0.8%. A capacitance of ≈ 2.4 pF gives an ENC of ≈ 230 e -, which leads to an energy resolution worse than 3%.

An ancillary detector can be designed for fusion-evaporation and/or direct reactions in inverse kinematics at energies of 20 MeV/u. An effort should be done to avoid duplicates and to develop convergent complementary set-ups The chips have ENC values which worsens the performance of the Si-pad detectors, limiting the energy resolution. The obtained results disagree with the technical characteristics given by the producer. R&D on ASIC’s and PSA. Conclusions Conclusions

SINTEF thickness 1.0 mm 6 x 21 pads typical pad size:1.8x1.8 mm 2 Bias Voltage: 150 ÷300 V AC coupled A guard ring to allow a more stable operation at full depletion. The pads are connected via strips to the bond pads located on one side of the detector, suitable for wire bonding to a PCB read-out board.

Tests of Si-Pad Detectors and Read-out ASIC Electronics Experimental set-up used to test the hybrid chips. The whole system is inserted in a closed metallic cage put to mass, to prevent the influence of the external electric field and light. The image on the right is the VA-DAQ read-out system which is connected to the parallel port of the PC.

MICRON thickness ~ 500 μm 5x12 pads pad size 3.75x3.75 mm 2 full depletion voltage: ~ 50V DC coupling As the detector was delivered completely naked, a self-made AC circuitry was used for the coupling either with the ASIC and the standard DAQ system. Device Type: IMAGE PIXEL ARRAY – 500

SummarySummary More realistic event generators are needed to make (usefull) simulations. The analysis of the experiment is still going on, looking for the actual value of the resolution, achievable in working conditions. Still waiting for thicker Si prototype. An in-beam test is going to be planned.

FHWM 69 keV 7.8 keV Doppler Correction Ref.: E.Farnea, F.Recchia. LNL Annual report 2003.

sectors Ge E E E slices rings E Simulated Results

Inverse Kinematics

keV FWHM 35 keV (single crystal) Experimental Data

Si-pad detectors for X-rays developed at UNICAM-PG-LNL Micron: 300  m, 12x5 pads of 4x5 mm 2 Sintef: 1 mm, 21x6 pads of 2x2 mm 2 Principal characterictics Solid angle: 4  Angular/spatial resolution: 1 to 2 mm Energy resolution: ~ 1 keV 60 keV Time resolution: ~ 10 ns (FWHM) Dynamic range: keV Rate and multiplicity: 1-10 kHz, 1-10 pads Solid angle: 4  Angular/spatial resolution: 1 to 2 mm Energy resolution: ~ 1 keV 60 keV Time resolution: ~ 10 ns (FWHM) Dynamic range: keV Rate and multiplicity: 1-10 kHz, 1-10 pads Ancillary for HPGe  -ray array AGATA

PAD2= AC coupled 8x32 pads 1x1 mm 2 Signal extracted on the opposite long sides to reduce strip length. 120  m 250  m 140  m