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The Lifetime Measurement of First 2 + State in 174 Os with LaBr 3 (Ce). 李聪博 1,2 等 指导教师:吴晓光 1 ,李险峰 2 1 中国原子能科学研究院 2 吉林大学. 2012-4-13 浙江湖州. CONTENTS. Introduction LaBr 3 :Ce Crystals and Test Experimental Electronics and Data analysis method Off-line Test with 152 Eu - PowerPoint PPT Presentation
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The Lifetime The Lifetime Measurement of First 2Measurement of First 2++
State in State in 174174Os with Os with LaBrLaBr33(Ce)(Ce)
李聪博 1,2 等指导教师:吴晓光 1 ,李险峰 2
1 中国原子能科学研究院2 吉林大学
2012-4-13 浙江湖州
CONTENTSCONTENTS IntroductionIntroductionLaBrLaBr33:Ce Crystals:Ce Crystals and Testand TestExperimental Electronics Experimental Electronics and Data analysis methodand Data analysis method
Off-line Test with Off-line Test with 152152Eu Eu In-beam ExperimentsIn-beam ExperimentsConclusionsConclusions
IntroductionIntroduction
A Large error bar
Neutron mid-shell
174Os
Os
IntroductionIntroduction1. Recoil distance method (RDM) with
Plunger devices. (ps - ~1ns)2. Triple-βγγ (t) coincidence method using
a mix of Ge, plastic, BaF2 or LaBr3(Ce) in β decay experiment. (>several Ps) H. Mach et al, Nucl. Instrum. Meth. A 280, 49 (1989).
3. A new experimental method Triple-γγγ (t) with LaBr3(Ce) and Ge in-beam experiments. (>several Ps)
174Os(21+) with lifetime 505(60) ps
(RDM). J. Gascon et al., Nucl. Phys. A 470, 230 (1987).
N. Mărginean, et al., Eur.Phys.J.A 46,329(2010)
LaBrLaBr33:Ce Crystals:Ce Crystals and and TestTest
crystals Dendity( gcm-3)
Light yield( ph/keV)
Decay time( n
s)
maximum emission( nm)
Energy resolution( %) 662k
eV
NaI:Tl 3.67 41 230 410 5.6CsI:Na 4.51 40 630 420 7.4CsI:Na 4.51 66 1000x800/6 550 6.6LaCl3:Ce 3.79 49 28 350 3.8LaBr3:Ce 5.0 63 16 380 2.8BGO 7.1 9 300 480 9.0LSO 7.4 26 40 420 7.9GSO 6.7 8 60 440 7.8YAP 5.5 21 30 350 4.3BaF2 4.9 2 0.8 225 10
LaBr3:Ce CrystalsLaBr3:Ce Crystals and and TestTest
CrystalscharacteristicsVolume: Four 30 × 30mm
Three 1 × 1 inch cylinder
LaBrLaBr33:Ce Crystals:Ce Crystals and and TestTest
Energy Resolution
LaBrLaBr33:Ce Crystals:Ce Crystals and and TestTest
Time Resolution
22Na
Experimental Electronics and Experimental Electronics and Data analysis methodData analysis method
Experimental Electronics Experimental Electronics and Data analysis and Data analysis
methodmethod1. FWHM
Sloping method
2. FWHM
H. Mach, R.L. Gill and M.Moszyinski, Nucl. Instrum. Meth. A 280, 49 (1989).
Off-line Test with Off-line Test with 152152EuEu
Off-line Test with Off-line Test with 152152EuEu
Deconvolution Fitting
T1/2=1.42(2)ns
1.39( 3) ns
In-beam ExperimentsIn-beam Experiments
28 150 174 4Si Sm Os n
35 144 176 1 2Cl Sm Pt p n
37 144 178 1 2Cl Sm Pt p n
In-beam ExperimentsIn-beam Experiments28 150 174 4Si Sm Os n
Cascade
In-beam ExperimentsIn-beam Experiments
Beams: 140 MeV
28Si
Target: 0.9mg/cm2
152Sm rolled onto
a12.5mg/cm2 Pb
backing
10 HPGe-BGO , 2
Planar HPGe and 7
LaBr3(Ce)
In-beam ExperimentsIn-beam Experiments
J.L. DURELL et al. Phys. Letter. B115 367(1982)
In-beam ExperimentsIn-beam Experiments
508(16)ps
In-beam ExperimentsIn-beam Experiments
Jing-ye Zhang et al., Phys. Rev. C 73, 037301 (2006)
A subshellstructure in the evolution of W and Os isotopic chains.
4A large increase
In-beam ExperimentsIn-beam Experiments
M. Rudigier et al., Nucl. Phys. A 847, 89 (2010).
In-beam Experiments
N.V. Zamfir et al. Phys. Letter. B357 515(1995)
4
P.Moller,J.R.Nix,W.D.Myers,W.J.Swiatecki,At.DataNucl.DataTables59(1995)185–381.
20 2 2 4~ (1 0.3604 0.9672 )Q
22
1 1 20( 2 : 2 0 ) ( ).16
eB E Q
241 1 1 1
4
( 0)( 2 : 2 0 ) ( 2 : 2 0 ).( )
( 0)Q
QB E B E
Q
In-beam ExperimentsIn-beam Experiments
In-beam Experiments
Suggested as +0.1174
+0.145
M. Rudigier et al., Nucl. Phys. A 847, 89 (2010).
P.Moller,J.R.Nix,W.D.Myers,W.J.Swiatecki,At.DataNucl.DataTables59(1995)185–381.
ConclusionsConclusionsThe lifetime of the first excited 2+ state in 174Os has been remeasured in fast time experiment and determined to be a greater accuracy, to be 508(16)ps. A deviation of the B(E2) value systematics in 174Os may hint a nuclear structure change, resulting a large increase in hexadecapole deformation (with +0.145).These explanations, from phenomenology at least, modify the expected trends. Other explanations, especially with microscopic model calculations, are needed.
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