isospin impurity of the isobaric analogue state of super-allowed beta decay experimental technique...
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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
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
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?
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)
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
Identification projectile fragmentsIdentification projectile fragments
7 to 8 identification parameters
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
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
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
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
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) -
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
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)
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
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….