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Isospin impurity of the Isobaric Analogue State of super-allowed beta decay
Isospin impurity of the Isobaric Analogue State of super-allowed beta decay
• experimental technique• isospin impurity determination
Bertram Blank, CEN Bordeaux-Gradignan ESNT, Saclay, April, 26-29, 2011
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The idea:The idea:
T, Tz- 1
T-3/2, Tz-3/2
T, Tz
Super-allowed decay
Proton emission
T - 1, Tz- 1
Gamma decay
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The idea:The idea:
52Co: T=2, Tz=-1
51Fe: T=1/2, Tz=-1/2
52Ni: T=2, Tz=-2
Super-allowed decay
Proton emission:T=1/2, Tz = -1/2
T= ½ + ½ T = 1, Tz = -1 T = 2
Gamma decay
Can one determine the isospin impurity of the IAS?
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Calcium: 37,36Ca
Titanium: 41,40,39Ti
Vanadium:43V
Chromium:45,44,43,42Cr
Manganese :47,46Mn
Iron:49,48,47,46,45Fe
Cobalt:51,50Co
Nickel:53,52,51,50,49,48Ni
Copper: 55Cu Zinc: 56,55,54Zn
Proton-rich nuclei in the region of Ca to NiProton-rich nuclei in the region of Ca to Ni
Mass region (20 Z 28 et Tz -3/2) 5 experiments at GANIL 23 isotopes studied (39Ti au 53Ni)
Mass region (20 Z 28 et Tz -3/2) 5 experiments at GANIL 23 isotopes studied (39Ti au 53Ni)
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Primary beam:58Ni @ 75 MeV/Aintensity: 3 - 4 Ae
SISSI target:natNi 200 mg/cm2
spectrometer LISE3 :degrader Be (50 m)Wien filter
detectionsetup
silicon telescopeidentification ofimplanted fragments
DSSSD (X-Y): 2 x 16 x 3 mm
- veto for light particles- residual energy, x-y position- energy loss
- time of flight: micro-channel plate detectors RF cyclotron
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Identification projectile fragmentsIdentification projectile fragments
7 to 8 identification parameters
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Proton and gamma branching ratios and energiesProton and gamma branching ratios and energies
41Ti
T
B1 B2
A
41Ti 41Ti
Rad
ioac
tivi
ty o
f 41
Ti
Rad
ioac
tivi
ty o
f 49
Fe
Correlation time
Protons
41TiContaminant from 49Fe and 45Cr
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Background subtraction for raysBackground subtraction for rays
49Fe 49Fe
Before After
Contaminants
Decay of 49Fe
Decay of 49Fe
C. Dossat et al., NPA 792 (2007) 18
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Spectroscopy of 52NiSpectroscopy of 52Ni
T1/2 = (40.8 ± 0.2) ms
Pp = (31.4 ± 1.5) %
• Ep = (2815 ± 23) keV • Ip = (0.9 ± 0.4) %
• Ep = (1349 ± 10) keV • Ip = (9.4 ± 1.3) %
• Ep = (1057 ± 11) keV • Ip = (2.9 ± 0.3) %
C. Dossat et al., NPA 792 (2007) 18
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Spectroscopy of 48FeSpectroscopy of 48Fe
T1/2 = (40.8 ± 0.2) ms
Pp = (31.4 ± 1.5) %
• Ep = (1013 ± 12) keV • Ip = (1.8 ± 0.3) %
• Ep = (2000-3000) keV • Ip = (1.4 ± 0.5) %
• Ep = (1500-1900) keV • Ip = (2.0 ± 0.4) %
C. Dossat et al., NPA 792 (2007) 18
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Isotope
Half-life (ms)Total proton branching ratio
(%)Mass excess via IMME
37Ca 181.7 ± 3.6 72.2(43) -36Ca 100.1 ± 2.3 51.2(10) -41Ti 82.6 ± 0.5 91.1 (6) -15.717(7)40Ti 52.4 ± 0.3 95.8 (13) -9.06(8)39Ti 28.5 ± 0.9 93.7(28) -43V 79.3 ± 2.4 < 2.5 -
45Cr 60.9 ± 0.4 34.4 (8) -19.49 (3)44Cr 42.8 ± 0.8 14.0 (9) -13.64 (2)43Cr 21.1 ± 0.4 92.5 (28) -1.92(6)42Cr 13.3 ± 1.0 94.4(50) -
47Mn 88.0 ± 1.3 < 1.7 -46Mn 36.2 ± 0.4 57.0 (8) -12.49 (3)49Fe 64.7 ± 0.3 56.7 (4) -24.67 (2)48Fe 45.3 ± 0.6 15.9 (6) -18.07 (5)47Fe 21.9 ± 0.2 88.4 (9) -7.08 (4) 46Fe 13.0 ± 2.0 78.7 (38) 0.76 (10)51Co 68.8 ± 1.9 < 3.2 -50Co 38.8 ± 0.2 70.5 (7) -17.59 (4)53Ni 55.2 ± 0.7 23.4 (10) -29.39 (4)52Ni 40.8 ± 0.2 31.4 (15) -22.64 (3)51Ni 23.8 ± 0.2 87.2 (8) -11.93 (7)50Ni 18.5 ± 1.2 86.7(39) -4.14 (3)49Ni 7.5 ± 1.0 83.4 (132) -
55Cu 27.0 ± 8.0 15.0 (43) -56Zn 30.0 ± 1.7 86.9(49) -55Zn 19.8 ± 1.3 91.0(51) -
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Proton emission from the IAS is isospin forbidden
Comparison of , and of for IAS :
• 48Fe : = 2.1 % - = 30% = 42 %• 52Ni : = 10 % - = 38% = 64 %
Determination of isospin impurities with these experimental data:
•
• (experimental, theory)
• ’p : Coulomb and centrifugal barrier penetration
• Sp = 1
Isospin impuritiesIsospin impurities
IASpI IAS
βthI
IASpI IAS
βthIIASpI IAS
βthIIASIIASI
ip'
iIASp
IAS
IS I I
I
pp
IAS
IASp
p'i I
I
S I
p
X IASp
IASβth
IASγ III
IASI
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Isospin impurity: example of 48FeIsospin impurity: example of 48Fe
= 2.1 %
= 42 %
II = 0.52 %
Measured energies (keV)
Predicted energies (keV)
EIAS 3037 (10) 2979
E (IAS – 1+) 2631 (1) 2458
E
(2+ - ground state)313.0 (5) 233
IASβthI
IASpI
W.A. Richter, B.A. Brown
IAS Shell model (48Mn)
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Isospin impurity: example of 52NiIsospin impurity: example of 52Ni
= 10 %
= 64 %
II = 19 %
Measured energy (keV)
Predicted energy (keV)
EIAS 2931 (10) 2796
Shell model (52Co)
IASpI
IASβthI
IAS
W.A. Richter, B.A. Brown
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neighboring nuclei: surprising…
however: shell-model study :
II(36Ca) = 0.4 %, II (40Ti) = 17.3 % (Theory Jyväskylä in sd shell)
similar treatment possible for many other nuclei: 45,44Cr, 46Mn, 49Fe, 53,51Ni….
II(48Fe) = 0.52 %, II (52Ni) = 19 %
Isospin impurity of IASIsospin impurity of IAS
B.A. Brown, N. Smirnova….
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