Title: Design study for a 4p ancillary detector for light charged particles to be used together with g-ray arrays in fusion-evaporation and direct reactions
1Design study for a 4p ancillary detector for
light charged particles to be used together with
g-ray arrays in fusion-evaporation and direct
reactions
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
C.M. Petrache Trento, January 16-20, 2006
2Physics Case
- Study of the structure of exotic nuclei using
secondary radioactive beams (SPES_at_LNL,
SPIRAL2_at_GANIL)
- using
- Fusion-evaporation reactions in inverse
kinematics - to measure
- Energy and Angle of light charged particles (p,a)
- with
- Ancillary detectors coupled with gamma arrays
using Direct reactions in inverse kinematics to
measure Energy and Angle of the recoiling light
particle
3AGATA
4TRACE
Fusion-evaporation -gt different from TIARA MUST
(transparent, high granularity forward,
low-energy threshold backward) Direct reactions
-gt similar characteristics like TIARA MUST
5AGATA reaction chamber
- 40 cm
- Large space
- for ancillary
- detectors
- electronics
6Monte Carlo simulations with GEANT4 for the
barrel geometry
7Main 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
- ASICs
- DSS
8Main 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.
9Detector Specifications
- Detector made of Silicon to minimize the
absorption of gamma rays, thin junction window
(0.1mm). - Geometries
- ?E Si-pad det. lt150 ?m thick, pad 2x2 mm2, strip
2 mm - E Si-pad det. gt1.5 mm thick, pad 2x2 mm2,
strip 2 mm - Dimensions 40 x 80 mm2
- Angular Resolution 1, 1-2 mm at 15 cm
- Energy resolution lt50 keV for 5 MeV a-particles
- Wide energy range 200 keV-20 MeV for p, 80 MeV
for a - Time Resolution 500 ps for A8 2 MeV/u
- Pulse shape analysis 2 GHz, gt10 bits
- Coupling AC
10Coupling with AGATA demonstrator
11Coupling with AGATA 2p
12Lateral faces8 DE-E modules with orthogonal
Si-strip
13Forward 4 DE-E modules with Si-pad
Backward 4 DE-E modules with Si-strip
14Transparency
EUCLIDES EdE Si-ball for charge particle
detection and identification. ?E 130 um E
1000 um
TRACE EdE Si-Pad for charge particle detection
and identification. ?E 150 um E 1500 um
15Goal checking the feasibility of tracking with
the first cluster prototype under (future) AGATA
working conditions.
16Ancillary device DSSD 32 rings 64 sectors
Ge detector first AGATA symmetric cluster (3
detectors)
17Evidence For Various Reactions
FWHM 300 keV
18in
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
19FHWM 33 keV (cluster) 15.6 keV (single)
7 keV 4.3
keV (single)
20Electronics
Number of channels 8000
Dynamic range for Light Charged Particles 0.2 -
20 MeVSi 56x103 - 6x106 e- 9 fC 1 pC
Ranges in silicon for alphas 60 MeV 1.5 mm 80
MeV 2.5 mm
Ranges in silicon for protons 15 MeV 1.5 mm 20
MeV 2.5 mm
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 RD
for ASIC with PSA
21Electronics
- 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.
Chip Board VA32C2-TA32CG VA_TA_HPD2_H7
546 VA32_HDR_11-TA32 VA_TA_HPD2 VATAGP3
128 channels, sparse read-out, range 18 fC
System Test VADAQ
22Tests 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 a-source
241Am source in air at 1 cm FWHM 500 keV _at_ 5.5
MeV (9.1)
Standard electronics a-source 241Am source
FWHM 70 keV _at_ 5.5 MeV (1.3)
23- 1 mm thick Sintef detector ASIC (VA32C2-TA32CG)
- ?-Sources 241Am, 57Co
- energy resolution 6 keV _at_ 60 keV (10)
24New Si-pad Detectors from IRST - Trento
STRIP 64 strips/side strips orthogonal on the
two sides strip pitch 500 µm Two different strip
width 300 µm (STRIP1) 200µm (STRIP2).
- Thickness 1.5 mm
- Thin junction window
- (up to 100200 nm)
- High resistivity
- (gt30 kO cm)
- Bias voltage 200300 V
- (multi guard rings)
- One single metal layer
- Near edge bonding contacts
strip1
PAD2
PAD1
strip2
PAD3
PAD1AC, 6x5 pads, 4x4 mm2 PAD2AC, 8x32 pads,
1x1 mm2 PAD3DC, 8x8 pads, 2x2 mm2
25PAD1 AC coupled 6x5 pads
4x4 mm2 Signal extracted on the opposite sides
to reduce strip length.
120 mm
500 mm
140 mm
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27Tests of Si-Pad Detectors and Read-out ASIC
Electronics
SINTEF
MICRON
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.
28Results 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.
29Equivalent 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.
30 Conclusions
- 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. - RD on ASICs and PSA.
31SINTEF
- thickness 1.0 mm
- 6 x 21 pads
- typical pad size1.8x1.8 mm2
- 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.
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34Tests 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.
35MICRON
Device Type IMAGE PIXEL ARRAY 500
- thickness 500 µm
- 5x12 pads
- pad size 3.75x3.75 mm2
-
- 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.
36Summary
- 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.
37 FHWM 69 keV 7.8 keV
38E
sectors
slices
E
E
Ge
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401381.75
41Si-pad detectors for X-rays developed at
UNICAM-PG-LNL
Micron 300mm, 12x5 pads of 4x5 mm2
Sintef 1 mm, 21x6 pads of 2x2 mm2
AGATA
Principal characterictics
Ancillary for HPGe g-ray array
- Solid angle 4p
- Angular/spatial resolution 1 to 2 mm
- Energy resolution 1 keV FWHM _at_ 60 keV
- Time resolution 10 ns (FWHM)
- Dynamic range 20 - 500 keV
- Rate and multiplicity 1-10 kHz , 1-10 pads
42PAD2 AC coupled 8x32 pads
1x1 mm2 Signal extracted on the
opposite long sides to reduce strip length.
120 mm
140 mm
250 mm