Observation of excited states in neutrondeficient cesium isotopes

1
Observation of excited states in
neutron-deficient cesium isotopes

• Paul Wady
• University of the West of Scotland

• Contents
• 112Cs
• Motivation np interactions
• Experimental details
• Overview of data analysis
• Experimental results
• 113Cs
• Preliminary results
• Summary of all results

IOP Nuclear Physics Conference 6th to 8th April
2009.
2
Area under investigation
3
Single particle states in the A120 region
P.J. Woods and C.N. Davids, Ann. Rev. Nucl. Part.
Sci. 47, 541 (1997)
Calculated deformation of 112Cs
Approximate neutron Fermi level
Approximate proton Fermi level
4
Evidence of p-n interaction Rotational alignments
?
(J.F. Smith et al., Phys. Rev. C 63, 024319
(2001))
?
5
Experimental details (Argonne)
.

• Reaction 58Ni(58Ni,p3n)112Cs
• Beam 58Ni at 260 MeV
• Target 565mg/cm2 58Ni foil
• Gammasphere- Gamma rays.
• Argonne FMA- residue A/q.
• DSSD residue P and a decay, for RDT
• Trigger DSSD OR 13g
• Beam from ATLAS at Argonne
• Number of events 4.6x109

6
Selection of 112Cs by recoil decay tagging
Time gate Tdecay lt1500 µs
Production cross-section 112Cs 50nb this
work500nb (R.D. Page et al., Phys. Rev. Lett.
Vol. 72 (1994) 1798)
8105 keV (Decay energy observed in this
work) 8077 keV (R.D. Page et al., Phys. Rev.
Lett. 72, 1798 (1994))
7
Observed decay time for 112Cs
47050 µs (Half-life 112Cs observed in this
work)500100 µs (R.D. Page et al., Phys. Rev.
Lett. 72, 1798 (1994))
8
Gamma rays selected by decay energy, decay time
and A/q ratio
641 keV ltEdecaylt 846 keV 67 µs ltTdecaylt1500 µs
PPAC gates wider gates
109I transitions (C.-H. Yu et al., Phys Rev. C
59, R1834 (1999)) (M. Petri et al., Phys. Rev. C
76, 054301 (2007))
9
Extended odd-odd cesium systematics
n(h11/2)?p(h11/2) bands
10
Rotational alignment plots
Harris parameters from A120 region J017.0
MeV-1h2, J125.8 MeV-3h4
11
Experimental details (Jyväskylä)

• Reaction 58Ni(58Ni,p2n)113Cs
• Beam 58Ni at 230 MeV
• Target 500mg/cm2 58Ni foil, with 100mg/cm2
  carbon backing
• Jurogam-I - Gamma rays.
• RITU- evaporation residue/ primary beam
  separation
• DSSD residue P and a decay, for RDT
• Triggerless TDR system
• Beam from K130 cyclotron

12
Preliminary observations of excited states in
113Cs
Eg (keV)
C.-H. Yu et al., PROTON-EMITTING NUCLEI Second
International Symposium PROCON 2003. AIP
Conference Proceedings 681.
13
Summary of Results

• 112Cs
• Decay rates of 112Cs observed with improved
  accuracy
• Decay energy of 112Cs observed with improved
  accuracy
• Initial level scheme of 112Cs produced
• Production cross section calculated
• Rotational alignments possibly partially observed
  due to low production cross-section
• 113Cs
• Decays of 113Cs observed
• Initial decay spectra produced

14
List of collaborators

• P.T. Wady and J.F. Smith,
• University of the west of Scotland.

• D. M. Cullen and S. J. Freeman, University of
  Manchester.

• T. Grahn, A. Grint, B. M. McGuirk, R. D. Page, J.
  Pakarinen, E. S. Paul, M. Petri and S. J. Rigby,
  University of Liverpool.

• C. J. Chiara, Washington University.

• M. P. Carpenter, R. V. F. Janssens, T. Lauritsen,
  C. J. Lister, A. P. Robinson, D. Seweryniak and
  S. Zhu , Argonne National Laboratory.

• S. Eeckhaudt, P. Greenlees, P. Jones, R. Julin,
  S. Juutinen, H. Kettunen, M. Leino, A.-P.
  Leppänen, P. Nieminen, M. Nyman, P. Rahkila, C.
  Scholey and J. Uusitalo, University of of
  Jyväskylä.

• R. Wadsworth, University of York.

15
Known decay schemes of 109I
(M. Petri et al., Phys. Rev. C 76, 054301 (2007))
(C.-H. Yu et al., Phys Rev. C 59 (1999))
16
Selection of 113Cs by recoil decay tagging
17
Observed decay time for 112Cs
Observed decay half-life 112CsT1/2500100 µs
(R.D. Page et al., Phys. Rev. Lett. Vol. 72 No.
12 (1994))
18
Yrast bands in neighbouring cesium isotopes
118Cs

• Unpaired proton and neutron are in the same
  subshell ?(h11/2) ? ?(h11/2)

116Cs
GS22 58Ni(64Zn,3pn) Phys. Lett. B (1997)
GSFMA6 58Ni(64Zn,apn) Phys. Rev. C (2006)
114Cs
GSFMA92 58Ni(58Ni,pn) Phys. Rev. C (2006)
19
112Cs proton decay literature

• Page et al, Phys. Rev. Lett. 72 1798 (1994)
• T1/2 500 100 ms
• Ep 807 7keV

Woods and Davids, Ann. Rev. Nucl. Part. Sci. (
1997 ).
Cross section for 58Ni(58Ni,p3n)112Cs 260
MeV0.5mb My observations 50nb
Area under investigation
20
A/q ratio (PPAC x)
21
Decay modes near the proton dripline at A110 and
the nuclei populated
116
56Ba
CN
55Cs
KEY Amass number Bhalf life Cdecay
branch Ddecay energy Edecay mode Fproportion
of IDd reaction products
113
a
54Xe
2.74s 0.04 (2.985MeV) 0.082
1.2
53I
52Te
1.7
51Sb
0.18
8.7
2.4
0.87
26
N60
N59
N58
N57
N56
N55
N54
N53
22
Recoil Decay Tagging (RDT)
After several half lives
a, b, g, p
23
Proton decay spectra
Tdecaylt 1500ms
109I t1/2100ms
113Cs t1/217ms
m
A/q
112Cs t1/2500ms
Edecay
24
Decay modes near the proton drip line at A110
116
56Ba
55Cs
KEY Amass number Bhalf life Cdecay
branch Ddecay energy Edecay mode
113
a
54Xe
2.74s 0.04 (2.985MeV)

53I
52Te


51Sb





N60
N59
N58
N57
N56
N55
N54
N53