Detection of X rays in the Neutron-Deficient Polonium Coulomb Excitation Experiments
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Detection of X rays in the Neutron-Deficient Polonium Coulomb Excitation Experiments Nele Kesteloot IKS KU Leuven SCK • CEN
description
Detection of X rays in the Neutron-Deficient Polonium Coulomb Excitation Experiments. Nele Kesteloot IKS KU Leuven SCK • CEN. Outline. The polonium isotopes Experimental campaign X rays Overview Origin K-vacancy creation in collision Corrections Normalization 206 Po 188 Hg - PowerPoint PPT Presentation
Transcript of Detection of X rays in the Neutron-Deficient Polonium Coulomb Excitation Experiments
Detection of X rays in the Neutron-Deficient Polonium Coulomb Excitation
ExperimentsNele Kesteloot
IKS KU LeuvenSCK • CEN
Miniball Workshop 2013 - CERN 2
Outline
● The polonium isotopes● Experimental campaign● X rays
●Overview●Origin●K-vacancy creation in collision●Corrections ●Normalization
●206Po●188Hg
●E0 transitions● Other pitfalls● Outlook 25th of October 2013
Miniball Workshop 2013 - CERN 325th of October 2013
The polonium isotopesThe polonium isotopes Experimental campaign X rays Outlook
Generalized
seniority
Shape coexisten
ce T.E. Cocolios et al. PRL 106:052503 (2011)
N =
116
M.D. Seliverstov et al., in preparation
Change in nuclear structure
Transition expected around
200Po
R. Julin et al JPG 27:R109 (2001)A.M. Oros et al NPA 645:107 (1999)(π1h9/2)2
Other pitfalls
Miniball Workshop 2013 - CERN 4
Experimental campaign
25th of October 2013
196Po 198Po 200Po 200Po 202PoBeam energy[MeV/u]
2.85 2.85 2.85 2.85 2.85
Target 104Pd 94Mo104Pd
104Pd 104Pd 94Mo104Pd
Beam purity 55(1)%
92(5)%
98.2(4)%
~99%
~98(40)%
Contaminant
196Tl 198Tl 200Tl 200Tl 202Tl
Beam time ~63h ~26h ~46h ~2h ~6hYear 2012 2012 2009 2012 2012
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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X rays – Overview
25th of October 2013
196Po on 104Pd 198Po on 94Mo 200Po on 104Pd
202Po on 104Pd 202Po on 94Mo 206Po on 104Pd
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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X rays – Origin
25th of October 2013
Conversion of observed 200Po gamma rays
X rays
Atomic production of K vacancy in ion-atom collision
0+
2+
0+
0
666
1137
200Po
E0 transition 0+2 0+
1
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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● Ion-atom collision gives rise to production of K vacancy
● Theoretical formula
●Scale proton-induced cross section to heavy projectile
●Change reference frame ●K-vacancy in projectile●Energy per nucleon remains unaltered
●Very sensitive to beam energy●Take energy loss in target into account
X rays – K-vacancy creation in collision
25th of October 2013
J.D. Garcia et al, RMP 45 No 2 (1973) 111
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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X rays – Corrections
● Empirical correction
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σ exp
/ σ th132Xe projectile on
target with Z protons
2.4 MeV/u3.6 MeV/u4.7 MeV/u5.9 MeV/u
Sexp = 0.070(15)Z
σ exp
/ σ th
Z
208Pb projectile on target with Z protons
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
H.-H. Behncke et al., Z. Phys. A 289 (1979) 333
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X rays – Corrections
● Geometrical correction
25th of October 2013
Detection range in center-of-mass frame
Sdet = 0.1439(18)
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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X rays – Normalization
25th of October 2013
● No observed low-lying excited 0+ states
● X rays●Conversion of observed
gamma lines●K-vacancy creation in
ion-atom collision
206Po on 104Pd
0+
2+
4+
2+ 4+
0
700.7
1162.2
1434.4
1177.8
206Po
4+1546.3
0+
2+
4+
2+ 2+
0
677.2
1248.6
1667.4
1302.5
202Po
(3,4)+1585.2
202Po on 104Pd
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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X rays – Normalization
● Compare to X rays in Hg coulex●Scale to 188Hg
25th of October 2013
Isotope Target Expected Observed Ratio202Po 104Pd 82(16) 250(66) 3.2(10)202Po 94Mo 59(14) 189(39) 3.0(10)206Po 104Pd 113(20) 296(135) 2.6(13)
Weighted average: 2.82(49)
Isotope Target Expected Observed Ratio188Hg 114Cd 709(180) 459(86) 0.65(20)188Hg 107Ag 98(25) 49(25) 0.50(28)188Hg 120Sn 1062(264) 535(91) 0.50(15)
Weighted average: 0.55(11)
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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X rays – E0 transitions in Po
25th of October 2013
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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X rays – E0 transitions in Hg
25th of October 2013
188Hg
114Cd 107Ag 120Sn186Hg
114Cd 107Ag 120Sn184Hg
112Cd 107Ag 120Sn182Hg
112CdObs
erve
d X
rays
/ E
xpec
ted
X ra
ys (%
)The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
Miniball Workshop 2013 - CERN 14
Other pitfalls
● Gamma ray detection efficiency ●Rapidly varying at low energies●Need for good efficiency calibration curve
●152Eu and 133Ba sources●Coincidence method
● Random subtraction●Big amount of randoms at low energies●Number of X rays very sensitive to p/r scaling factor!
●Correct propagation of error bars is crucial
● Fit of X-ray peaks25th of October 2013
The polonium isotopes Experimental campaign X rays OutlookOther pitfalls
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● Multiple origins for X rays in coulex data●Conversion of gamma lines●E0 transition between two 0+ states●K-vacancy creation in ion-atom collision
●Theory as qualitative basis●206Po/188Hg as normalization
● Correct assessment of X rays is crucial●Number of E0 transitions determines population of 0+
2 state● Influence on extracted matrix elements
● Normalization factors in other data sets●Pb coulex●Rn coulex
25th of October 2013
Conclusion and OutlookThe polonium isotopes Experimental campaign X rays OutlookOther pitfalls
Miniball Workshop 2013 - CERN 1625th of October 2013
B. BastinE. ClementN. Lecesne
N. BreeH. De WitteJ. DirikenL. GaffneyM. HuyseP. Van DuppenK. Wrzosek-Lipska
V. FedosseevB. MarshE. PiselliE. RapisardaM. SeliverstovT. StoraD. VoulotF. Wenander
T. GrahnJ. KonkiJ. Pakarinen
P. ReiterB. SiebeckN. Warr
T. Kröll, Technische Universität DarmstadtP. Butler, University of LiverpoolM. Scheck, University of West Scotland, PaisleyM. Zielinska, CEA Saclay
Thank you!
Miniball Workshop 2013 - CERN 1725th of October 2013
γγ coincidences in 198Po
0+
2+
2+4+
0+
0
604.9
1158.4 1039.1
816
198Po
Gate on 605 keV
Gamma energy (keV)
Num
ber o
f cou
nts
/ 2 k
eV
Miniball Workshop 2013 - CERN 1825th of October 2013
γγ coincidences in 196Po
0+
2+
2+4+
0+
0
463.1
891 859.1
558
196Po
Gate on 463 keV
