UNIVERSITY OF JYVÄSKYLÄ
Studies of single-particle
properties in Te nuclei above
the Z = 50 shell gap through
neutron-transfer reactions
Tuomas Grahn (University of Jyväskylä)
Bob Wadsworth (University of York)
Bo Cederwall (KTH Stockholm)
Proposal for INTC
31.10.2012
UNIVERSITY OF JYVÄSKYLÄ
Nuclei above N=Z=50
 Atomic nucleus is the only quantum system in which
unlike fermions can occupy identical orbitals.
 In the region above N=Z=50, valence nucleons occupy
orbitals with large spatial overlap.
 Monopole p-n interaction between the proton g7/2(j<),
neutron 2d5/2 (j> ) (or vice versa) and neutron h11/2 (j> )
orbitals expected to be strong.
UNIVERSITY OF JYVÄSKYLÄ
Trans-Sn region
Seniority scheme/single-particle
structures at N=82.
Vibrational collectivity at the neutron
mid shell.
Collectivity/single-particle structures
(?) as N=Z=50 is approached.
Recent lifetime measurement in
108Te ⇒ collectivity decreases.
Active orbitals with
strong spatial overlap
Development
of collectivity
driven by
single-particle
properties
UNIVERSITY OF JYVÄSKYLÄ
Odd-mass Te and Sb systematics
113Te115Te
119Te
Assumed neutron states
Assumed proton states
UNIVERSITY OF JYVÄSKYLÄ
Objectives
d(118Te,p)119Te
d(114Te,p)115Te
d(112Te,p)113Te
Position of the
single-particle
orbitals
Single-particle
occupancies,
distribution of the
main strengths at
low spin.
Better
understanding
of the protonneutron
interaction
Systematic
studies through
the neutrondeficient Te
nuclei
UNIVERSITY OF JYVÄSKYLÄ
Experimental details
 HIE-ISOLDE radioactive beams of neutron-deficient
Te: 5 MeV/u with A/q=4 (optimised for EBIS & Linac).
 Beams: 112Te, 114Te, 118Te with 106-107 pps primary
yields from HfO2 or CeO2 ISOLDE targets, ionised with
RILIS laser ion source. TAC: Beam purity of 90%
required. If problem, proton on/off mode possible.
 One-neutron transfer reactions on CD2 target (~150
µg/cm2) in inverse kinematics.
 Momentum analysis of the outgoing protons with the
Solenoidal spectrometer.
UNIVERSITY OF JYVÄSKYLÄ
Solenoidal spectrometer
 Outgoing protons will be
backward focused.
 Protons will travel in different
helical orbits in 3 T
solenoidal magnetic field
depending on their
momentum.
 Protons will be detected in
position sensitive detectors.
p
beam
PSD
target
Angular distributions
of the outgoing
protons.
UNIVERSITY OF JYVÄSKYLÄ
Angular distributions 5.5 MeV/u
 Energy spread of the
HIE-ISOLDE linac < 0.7%
⇒Energy resolution ~70
keV.
 Energy resolution can be
recovered using thinner
targets (cases where the
yield is high).
ΔL=2
11/2+ ΔL=5
5/2+
113Te
B. Kay et al. PRC 84, 024325 (2011)
7/2+
0+
ΔL=4
112Te
UNIVERSITY OF JYVÄSKYLÄ
Count rate estimate
 ΔL = 2 transfer: σtotal=13 mb with 5.5 MeV/u beams.
 150 μg/cm2 target thickness. With
112,114Te
thicker
targets can be used to compensate the lower yields.
 118Te requires a thin (< 100 μg/cm2) target for sub-100
keV resolution.
 70% proton detection efficiency.
⇒1000 counts in the proton peak in about 21 shifts (1
week).
d(112Te,p)113Te d(114Te,p)115Te d(118Te,p)119Te
Request
21 shifts
15 shifts
6 shifts
Total
42 shifts
UNIVERSITY OF JYVÄSKYLÄ
Summary & Outlook
 We propose to study the single-particle properties of
low-energy excitations in neutron-deficient Te nuclei.
 Methodology: one-neutron transfer reaction in inverse
kinematics with 112,114,118Te beams at HIE-ISOLDE.
 Instrumentation: Solenoidal spectrometer to be
constructed (similar to HELIOS at Argonne National
Laboratory).
 Following LoI I-112 it is our long-term plan to include
the (d,t) and (d,3He) studies and push (d,p)
measurements towards N=50.