Nuclear Spectroscopy with AGATA
J. Gerl
GSI
October 12, 2012
NUSTAR Week 2012
VECC Kolkata
India
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AGATA
4 -array for Nuclear Physics Experiments at accelerators providing
radioactive and stable beams
Main features of AGATA
Efficiency: 43% (M =1) 28% (M =30)
today’s arrays ~10% (gain ~4)
Peak/Total: 58% (M=1)
today
~55%
5% (gain ~1000)
49% (M=30)
40%
Angular Resolution: ~1º 
FWHM (1 MeV, v/c=50%) ~ 6 keV !!!
today
~40 keV
Rates: 3 MHz (M=1) 300 kHz (M =30)
today
1 MHz
20 kHz
• 180 large volume 36-fold segmented Ge crystals in 60 triple-clusters
• Digital electronics and sophisticated Pulse Shape Analysis algorithms allow
• Operation of Ge detectors in position sensitive mode  -ray tracking
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-ray Tracking Arrays
Electrically
segmented HPGe
detectors
Identification of the
individual interaction points
(x,y,z,E,t)i


 

Digital electronics
to record and
process segment signals
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Reconstruction of tracks
evaluating permutations
of interaction points
Deconvolution of the recorded
waves through comparison
with reference signals
A3
A4
A5
B3
B4
B5
C3
C4
C5
CORE
measured
calculated
Energy and direction
of -rays
3
AGATA detector element
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4
AGATA Preamplifier
Core Preamplifier
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5
Agata Triple Cluster
- integration of 111 high resolution
spectroscopy channels
- cold FET technology for all signals
-development of 36-fold segmented
- encapsulated detectors
Challenges:
- mechanical precision
- heat development
- LN2 consumption
- microphonics
- noise, high frequencies
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A. Wiens et al. NIM A 618 (2010) 223–233; D. Lersch et al. NIM A 640(2011) 133-138
6
AGATA: Digital Electronics
(7.6GB/s/crystal)
Global
Triggering
System
GTS
LAN to the disk servers
Computer farm
in the DAQ container
20 m long optical fibers
10 m long MDR cables
100Mhz, 14 bit
Synchronous &
continuous
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Digital proc. electronics
in the DAQ container
80 m long optical fibers
Digitisers
in the experimental hall
Triggering
Energy
Trace capture
Preprocessing
(10 kB/evt/crystal) PSA
Tracking
Clock &
Trigger validation
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Pulse Shape Analysis concept
A3
A4
A5
(10,10,46)
B3
B4
B5
(10,30,46)
C3
C4
C5
y
C4
CORE
B4
measured
D4
791 keV deposited in segment B4
A4
E4
F4
z = 46 mm
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8
x
Pulse Shape Analysis concept
A3
A4
A5
B3
B4
B5
(10,10,46)
C3
C4
C5
y
C4
CORE
measured
calculated
791 keV deposited in segment B4
B4
D4
A4
E4
F4
z = 46 mm
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9
x
Pulse Shape Analysis concept
A3
A4
A5
B3
B4
B5
(10,15,46)
C3
C4
C5
y
C4
CORE
measured
calculated
D4
A4
E4
791 keV deposited in segment B4
19
B4
F4
z = 46 mm
10
x
Pulse Shape Analysis concept
A3
A4
A5
B3
B4
B5
(10,20,46)
C3
C4
C5
y
C4
CORE
measured
calculated
791 keV deposited in segment B4
B4
D4
A4
E4
F4
z = 46 mm
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11
x
Pulse Shape Analysis concept
A3
A4
A5
B3
B4
B5
(10,25,46)
C3
C4
C5
y
C4
CORE
measured
calculated
791 keV deposited in segment B4
B4
D4
A4
E4
F4
z = 46 mm
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12
x
Pulse Shape Analysis concept
A3
A4
A5
B3
B4
B5
(10,30,46)
C3
C4
C5
y
C4
CORE
measured
calculated
791 keV deposited in segment B4
B4
D4
A4
E4
F4
z = 46 mm
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13
x
Pulse Shape Analysis concept
A3
B3
A4
B4
A5
B5
Result of
Grid Search
algorithm
(10,25,46)
C3
C4
C5
y
C4
CORE
measured
calculated
791 keV deposited in segment B4
B4
D4
A4
E4
F4
z = 46 mm
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x
1. Campaign at LNL Legnaro, Italy
2009 - 2011
AGATA coupled to PRISMA
May 2011
AGATA Demonstrator
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Doppler correction capabilities
Inelastic scattering
17O @ 20 MeV/u on 208Pb
F
O
dE (MeV)
N
a
16O
No Dopp Corr
Crystal Centers
Segment Centers
PSA+Tracking
C
B
Be
Li
TKE (MeV)
R.Nicolini, D.Mengoni
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The Experimental Campaign at LNL
Isospin Mixing
in 80Zr
Octupole-deformed
Ra and Th nuclei
Neutron-rich nuclei in
the vicinity of 208Pb
n-rich Th and U
Pygmy and GQR states
g.s. rotation
in Dy, Er, Yb
High-lying states
in 124Sn and 140Ce
protons
Molecular
structure
of 21Ne
Shape transition
in 196Os
n-rich
nuclei
Proton
drip-line
Coulex
of 42Ca
N=51 nuclei
Neutron-rich nuclei
populated by fission
Lifetimes of the
n-rich Cr isotopes
Lifetimes near the
island of inversion
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neutrons
Lifetime of the
6.792MeV state in 15O
Lifetime
of 136Te
Neutron
drip-line
Order-to-chaos
transition in 174W
N=84 isotone
140Ba
19 (+3)
exp.
148 days
Lifetimes in n-rich
Ni, Cu and Zn isotopes
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2. Campaign at GSI Darmstadt, Germany
2012--2014
Hector
LYCCA
AGATA
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Relativistic Coulomb excitation / fragmentation
112Sn
Coulomb
interaction
→Au
excited
nucleus
Prefragment
Equilibrated
nucleus
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Improvements
production
primary int.
selection
identification
rate capability
spectroscopy
 tracking
implantation /
reaction
granularity /
active target identification
ToF
 detectors
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Calorimeter
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AGATA at GSI set-up
Challenge: FRS beam size!!!
AGATA S2 Geometry
=
+
10 triple Cluster
+
5 double Cluster
S2' Geometry:
Pph ≤ 17%; E = 0.4 %
( sensitivity gain 30x RISING)
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AGATA 1 geometry: angular dependence of efficiency
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LYCCA-1
Target position
Wall position
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Wall E-E
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80Kr
Coulomb Excitation
E(Kr) = 150 AMeV
I(max) = 30 kHz
15 AGATA crystals
nominal target position
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PRESPEC-AGATA Campaign
May 2010: Presentation of 35 LoIs
Discussion in 6 working groups
Selection of first round proposals:
Physics, complexity, readiness
126
210,212Pb
82
202Pt
Os, W, …
protons
102-108Sn
132Sn,131In
50
92-96
124-128Cd
Pd
96-98Cd
76Sr 80Zr
isospin triplets
A=46, 62, 66
85Br
N=50
68,74Ni
64-68Fe
20
58-64
54,55Sc Cr
48Ar
8
2
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32Mg
20
2 8
120-122Pd
108-112Mo
104-108Zr
70,72Zn
28
44Cr, 52Fe
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132-136Te
50
neutrons
82
 Evolution of collectivity near 208Pb
 Shell structure near 78Ni, 100Sn, 132Sn
 Development of nuclear collectivity
 Shell evolution in light nuclei
 Nuclear structure at the N=Z line
 M1, E1, E2, E3 strength
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AGATA 1 at GANIL
2014 - 2016
In G1 coupled to VAMOS (and EXOGAM2 if
needed): SIBs, RIBs
At the intermediate focal plane of
S3: SIBs
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Acknowledgements
•
•
•
•
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Huge technical achievement
Many people and laboratories
Ongoing
Physics
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Acknowledgements
AGATA – Advanced Gamma Tracking Array
Nuclear Instruments and Methods in Physics Research A 668 (2012) 26–58
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