Development of ORRUBA - an Array for Transfer Measurements Development of ORRUBA - an Array for Transfer Measurements at the HRIBF for Nuclear Astrophysicsat the HRIBF for Nuclear Astrophysics
Steven D. Pain
Rutgers University
ORNL, October 2006
• Motivation
– N82 (d,p) experiments
• Development of ORRUBA
• First RIB data with ORRUBA
Neutron magic-number nuclei at waiting points
HRIBF yields
N=82
ORRUBA motivationORRUBA motivation
Requirements of ORRUBARequirements of ORRUBA
5
10
15
20
0
Yie
ldProton Angular Distribution
5
10
20
25
0
Ene
rgy
(MeV
)
15
0 60 90 120 150 180Laboratory Angle (deg)
30
• High Solid Angular Coverage
132Sn(d,p) @ 4.5 MeV/A
Proton Energy-Angle Systematics
• Good energy and angular resolution
• Large dynamic range
Requirements of ORRUBARequirements of ORRUBA
Protons from (d,p)
Elastically scattered carbon
Elasticallyscattered protons
Elastically scattered deuterons
Oak Ridge Rutgers University Barrel Array (ORRUBA) DesignOak Ridge Rutgers University Barrel Array (ORRUBA) Design
• 2 rings – < 90°: 12 telescopes (1000m R + 65m NR)
– > 90°: 12 detectors (500m R)
• 324 channels in total (288 front side, 36 back side)
ORRUBA Detector DesignORRUBA Detector Design
4 strip resistive detectors
8 strip non-resistive detectors
Prototype ORRUBA DetectorsPrototype ORRUBA Detectors
Have 1/3 detectors in house:• Correct operation of detector (measurement of position and energy independently)
• Energy Resolution
• Position Resolution
• Depletion Depth for thick detectors
Perform tests to determine:
• Thirteen 1000m detectors
• Several 65m detectors
• One 500m detector
• Number of prototypes
10001000m Detector Performance - Depletionm Detector Performance - Depletion
Ene
rgy
(a.u
.)
Position (a.u.)
particles into junction face particles into back face
MeV -particles only penetrate 30m into detector
Detector not fully depletedDetector not fully depleted
Either increase energy, or use more penetrating particles
Regions of poor charge collection20 V60 V100 V140 VFull bias80 V
Position (a.u.)
Ene
rgy
(a.u
.)
Proton Scattering TestsProton Scattering Tests
Proton Scattering TestsProton Scattering Tests
11.5 MeV12.0 MeV
Position (a.u.)
Ene
rgy
(a.u
.)
Position (a.u.)
Ene
rgy
(a.u
.)
Depletion DepthsDepletion Depths
Effect limited to back 10% of detector
Effect results in < 7% limit in maximum energy
68 keV FWHM on 11.5 MeV protons0.5mm FWHM on 11.5 MeV protons
Position (a.u.)
Ene
rgy
(a.u
.)Detector Test ResultsDetector Test Results
• Detectors perform well, with good energy and position resolution
• Detectors deplete >90% of their volume
500m detectors just out of implant stage
1000m Detector 1000m Detector
Thinner Detectors
• 65m non-resistive detectors for E layer, with greater segmentation (8 strips)
• Detectors at assembly stage
124124Sn(d,p)Sn(d,p)125125Sn ORRUBA Test SetupSn ORRUBA Test Setup
550 MeV 124Sn
124124Sn(d,p)Sn(d,p)125125Sn ORRUBA Test SetupSn ORRUBA Test Setup
1000m + 65m
300m
500m
1000m
100g CD2 target @ 60°
124124Sn(d,p)Sn(d,p)125125Sn ORRUBA Test Data – 1000Sn ORRUBA Test Data – 1000m detectorm detector
80 90 110100 120 130 140
2.5
5.0
7.5
10.0
Lab Angle (deg)
Ene
rgy
(MeV
)
Excitation Energy (MeV)0 1 4 53
Cou
nts
2
CoM resolution ~150keV
132132Sn(d,p) SimulationsSn(d,p) Simulations
Total CoM Resolution ~ 220 keV
E resolution ~ 65 keV
Pos resolution ~ 110 keV
Target ~ 155 keV
CoM Resolution (lab< 80°) ~ 175 keV
E resolution ~ 55 keV
Pos resolution ~ 80 keV
Target ~ 135 keV
ORRUBA Performance – on-line ORRUBA Performance – on-line 132132Sn(d,p)Sn(d,p)133133Sn dataSn data
SummarySummary
• Measurement of (d,p) reactions on heavy fission fragments requires high-solid angular coverage around 90°, with high resolution in energy and angle
• ORRUBA developed to meet these requirements, and be as flexible as possible
• Over 1/3 of detectors in house – arriving currently
• First (d,p) data taken with ORRUBA detectors. CoM resolution of 150 keV achieved with a 100g/cm2 target @ 60 degrees
• Early implementation of ORRUBA currently employed in the 130,132Sn(d,p) experiments
J.A. Cizewski, R. Hatarik, K.L. Jones, S.D. Pain, M. Sikora, J.S. ThomasRutgers University
M.S. JohnsonOak Ridge Associated Universities
D.W. Bardayan, J.C. Blackmon, C.D. Nesaraja, M.S. Smith, D. Shapira, F. LiangOak Ridge National Laboratory
R.L. KozubTennessee Tech. University
J. James, R.J. LivesayColorado School of Mines
A. Chae, Z. Ma, B.H. MoazenUniversity of Tennessee
W.N. Catford, T. SwanUniversity of Surrey
CollaboratorsCollaborators
Proton Scattering TestsProton Scattering Tests
ORRUBA Mount PhotosORRUBA Mount Photos
ORRUBA Mount PhotosORRUBA Mount Photos
Proton Scattering TestsProton Scattering Tests
Position
Ene
rgy
Angular Straggling MeasurementsAngular Straggling Measurements
1.2mm FWHM on 5.85 MeV protons
Angular straggling negligible at ~5 MeV
• 1000m stopping at forward angles
• 65m non-resistive dE at forward angles
ORRUBA Vacuum Chamber Cut-awayORRUBA Vacuum Chamber Cut-away
Target Manipulator
Preamplifier feedthroughs
Detectors mounted from preamplifier ring, on linear bearings, to allow detector access, without un-cabling
Possible to mount SIDAR upstream, to cover more backward angles, via second preamplifier ring
Beam Preamplifiers
Position (a.u.)
Ene
rgy
(a.u
.)
10001000m Detector Performance – m Detector Performance – particle tests particle tests
Guard ring effect (appears around 50V bias) independent of deposited energy 1.2 MeV
Position (a.u.)
Ene
rgy
(a.u
.)
10001000m Detector Performance – m Detector Performance – particle tests particle tests
Guard ring effect (appears around 50V bias) independent of deposited energy 1.2 MeV
ORRUBA ComparisonORRUBA Comparison
• ORRUBA gives ~80% coverage over the range 47° →132°
• Pre-existing setup gives <30% coverage over the range 60° → 120°
• Factor of ~4.5 times the solid angular coverage
• Can perform experiments with more exotic (weaker) beams for given beam-time
• Gain improved statistics from similar intensities
• Can perform experiments with similar beam intensities with less beam-time
ORRUBA Vacuum Chamber and PreamplifiersORRUBA Vacuum Chamber and Preamplifiers
Preamplifier ring
Preamplifier
Large cross target chamber
Rails
Small cross for diagnostic detector
Preamplifier ring
ORRUBA + SIDAR ArrangementORRUBA + SIDAR Arrangement
Target plane
Beam
91° - 132° 149° - 168°48° - 89°
Measure (d,p) either side of N=82, at Z=50
Measurements around N=82 more experimentally challenging
Measurements of 130Sn(d,p) and 132Sn(d,p) due to be performed imminently
5
15
20
30 60 90 120 150 lab (deg)
0
10
dd
(
mb/
sr)
Forward c-o-m ↔ back lab
130,132130,132Sn(d,p) ExperimentsSn(d,p) Experiments
Want to measure around 90o
Motivation for Developing ORRUBAMotivation for Developing ORRUBA
• Experiments on fission fragments must be performed in inverse kinematics
• Inverse kinematics results in forward peaks in the (CoM) angular distributions being dispersed over large range of back angles in the lab frame
• The effects of the strongly inverse kinematics are dominant → suggests a general purpose array design
• Measure excitation energies of states populated in the final nucleus with good resolution (~200keV due to target thickness effects)
• Measure proton angular distributions (ℓ transfer + spectroscopic information)
130,132130,132Sn(d,p) SetupSn(d,p) Setup
ORRUBA telescopes
ORRUBA telescopes
134134Te(d,p) MotivationTe(d,p) Motivation
U. Ott, Planetary and Space Science 49 (2001) 763
Pre-solar diamond grains • Overabundance of light and heavy Xe isotopes
• Heavy isotope anomaly: relative excesses of 134Xe and 136Xe do not correspond to average r-process abundances
Suggested explanations:
• Formation in intermediate neutron flux environment (between s & r process)
• Rapid separation of Xe from its precursors (Te and I) in supernova ejecta
• Low entropy r-process
134Xe 135Xe 136Xe
133I 134I 135I
132Te 133Te 134Te
N=82
136I
135Te 136Te
Effect of structure around N=82 shell closure
(d,p) on r-process Nuclei(d,p) on r-process Nuclei
From (d,p)Q-values, Ex, ℓ-values,
Spec Information
Calculate (n,γ) cross section(e.g. TEDCA)
Use to modify residual interactions in nuclear structure (shell) model
Improve global masses for n-rich nuclei
Input into SupernovaCode
Si-36 Custom Preamplifier Unit DesignSi-36 Custom Preamplifier Unit Design
Inputs
140140m Detector Tracesm Detector Traces
Position (a.u.)
En
erg
y (a
.u.)
Position (a.u.)
En
erg
y (a
.u.)
Position (a.u.)
En
erg
y (a
.u.)
0.5s 1.0s 1.5s
Effect of Shaping Time – 140Effect of Shaping Time – 140m detectorm detector
Position (a.u.)
Co
un
ts
Position (a.u.)
Co
un
ts
Position (a.u.)
Co
un
ts
5858Ni(d,p)Ni(d,p)5959Ni Test @ 250 MeVNi Test @ 250 MeV
58Ni
p
CD2 (~150 g/cm2 eff.)
1000m ORRUBA65m
ORRUBA
• First (d,p) data taken with ORRUBA detectors
• Stable beam
• 58Ni selected for convenience of acceleration
5858Ni(d,p)Ni(d,p)5959Ni Test @ 250 MeVNi Test @ 250 MeV
58Ni
p
CD2 (~150 g/cm2 eff.)
1000m ORRUBA65m
ORRUBA
100
0
Ene
rgy
Loss
(a.
u.)
300
200
100 200 300 400
400
Residual Energy (a.u.)0
4
0
Pro
ton
Ene
rgy
(a.u
.) 12
8
Angle (deg)80 100 120 140
5858Ni(d,p)Ni(d,p)5959Ni Test @ 250 MeVNi Test @ 250 MeV
58Ni
p
CD2 (~150 g/cm2 eff.)
1000m ORRUBA65m
ORRUBA 4
0
Pro
ton
Ene
rgy
(a.u
.) 12
8
Angle (deg)80 100 120 140
ASICsASICs
WashU (St Louis)/MSU ASICs system
• Preamps, discriminators, logic and analog circuits all on one (16 channel) chip
• 2 chips per chip board
• 16 chip boards per motherboard
• Multiplexed analog signals → single flash-ADC for entire system
• Dramatic cost reduction per channel compared with conventional electronics
• External preamps (need high gain)
Designed for non-resistive, low capacitance Si detectors
ASICsASICs
Fission Fragment Beam ProductionFission Fragment Beam Production
1. Createnucleus of interest
2. Transport to ion source
3. Ionize atoms
4. CreateNegativeIons
