186,187,188 os resonance analysis at n_tof
DESCRIPTION
4 December 2006. 186,187,188 Os resonance analysis at n_TOF. Kaori Fujii, P.M.Milazzo (INFN Trieste, Italy) M.Mosconi, F.K äppeler (FZK, Germany) A.Mengoni (IAEA, CERN). Outline. Os capture measurement at n_TOF resonance analysis - PowerPoint PPT PresentationTRANSCRIPT
K.Fujii n_TOF meeting 1
186,187,188Os resonance analysis at n_TOF
Kaori Fujii, P.M.Milazzo (INFN Trieste, Italy)
M.Mosconi, F.Käppeler (FZK, Germany)
A.Mengoni (IAEA, CERN)
4 December 2006
K.Fujii n_TOF meeting 2
Outline
Os capture measurement at n_TOF resonance analysis
“Estima” method (l-wave character analysis)
parameters estimation with SAMMY statistics analysis
average level spacing (D)
strength function (S)
K.Fujii n_TOF meeting 3
Os capture cross sections experiment→ application for Re/Os cosmo-chronometer
measurement on August 2003186Os(2g,79%), 187Os(2g,70%),188Os(2g,95%)
(n,γ) detection : 2 × C6D6 scintillators
Major part of the analysis → M.Mosconi Resonance region analysis → K.Fujii
K.Fujii n_TOF meeting 4
Os yields
186Os187Os 188Os
M.Mosconi
En(eV)
K.Fujii n_TOF meeting 5
Os Resonance analysis
Reference (resonance parameter) Neutron Cross Sections Mughabghab 1984 , (2006)
Low energy neutron physics Sukhoruchkin 1998
186Os (I=0) En ~ 3.3keV (~130 resonances)187Os (I=1/2) En ~ 1.0keV (~180 resonances)188Os (I=0) En ~ 5.0keV (~110 resonances)
K.Fujii n_TOF meeting 6
Estima method (l-wave character analysis)186Os 187Os 188Os
All resonances are evaluated “s-wave”
gΓn/(En)1/2 > 10 V1 <gΓn1> confident s-wave
gΓn/(En)1/2 > V1 <gΓn1> likely s-wave
V1=(kR)2/(1+(kR)2)
K.Fujii n_TOF meeting 7
Resonance analysis with SAMMY186Os 187Os 188Os
Reference to the transmission experimental data (En,Γn)
189Os
En(eV)+ n_TOF data
-- SAMMY fit
K.Fujii n_TOF meeting 8
Distribution of Γγ (s-wave)
186Os 187Os 188Os
<Γγ0> = 45.09 meV <Γγ0> = 65.54 meV <Γγ0> = 49.51 meV
Γγ (meV)
60±4 meV (Mughabghab)
76±4 meV (Mughabghab)
82±4 meV (Mughabghab)
K.Fujii n_TOF meeting 9
Cumulative sum of the number of resonances (staircase)
D0 = 25.55 eV
D0 = 5.89 eV
D0 = 47.45 eV
D0 : s-wave average level spacing
ΔE / N-1 (N: resonance numbers)
D0= 24.9±0.4 eV
(Mughabghab)
D0= 4.56±0.2 eV
(Mughabghab)
D0= 40±2 eV
(Mughabghab)
K.Fujii n_TOF meeting 10
s-wave strength function - 1(staircase plot of gΓ0
n
summation)Staircase plot (186Os)
y = 0.000260x + 0.118483
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0 500 1000 1500 2000 2500 3000 3500 4000
En(eV)
Su
mm
atio
n o
f g
G^0
_n
Staircase plot (187Os)
y = 0.000361x + 0.0012360.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 200 400 600 800 1000 1200
En(eV)
Su
mm
atio
n o
f g
G^0
_n
Staircase plot (188Os)
y = 0.000235x + 0.119022
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
0 1000 2000 3000 4000 5000 6000
En(eV)
Su
mm
atio
n o
f g
G^0
_n
S0(10-4)
186Os 2.60
187Os 3.61
188Os 2.35
186Os
188Os
187Os
En (eV)
En (eV)
En (eV)
S0=<gΓ0n>/<D0>
Γ0n = Γn(1/E0)1/2
K.Fujii n_TOF meeting 11
s-wave strength function -2 S0 : s-wave strength function : <gΓ0
n>/<D0>
(Γ0n = Γn(1/E0)1/2 : reduced neutron width)
<D0> <gΓ0n> S0 (10-4)
186Os 25.55 7.30 2.86±0.35187Os 5.89 2.10 3.56±0.38188Os 47.45 11.59 2.44±0.33
S0(10-4) staircase
S0(10-4) (Mughabghab)
2.60±0.32 2.3±0.32
3.61±0.39 3.04±0.35
2.35±0.33 2.39±0.36
Preliminary!
n_TOF data
K.Fujii n_TOF meeting 12
Summary
Os resonance parameters estimated
<Γγ> : ~20% less than previous data Statistics analysis going on
(average level spacing, strength function…) astrophysics application :
→ MACS → the age of the universe