Research group: R.Broda, B.Fornal, W.Królas, T.Pawłat, J.Wrzesiński
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Transcript of Research group: R.Broda, B.Fornal, W.Królas, T.Pawłat, J.Wrzesiński
Research group:
R.Broda, B.Fornal, W.Królas, T.Pawłat, J.Wrzesiński
H.Niewodniczanski Institut of Nuclear Physics PAN-KRAKOW
Collaboration with the INFN LNL Legnaro
Tandem and ALPI LinacGASP, PRISMA-CLARA spectrometer
Spectroscopy of hard-to-reach nuclei with
deep-inelastic heavy-ion reactions
Neutron-rich nuclei produced Neutron-rich nuclei produced in deep-inelastic processes in deep-inelastic processes
Beams of heavy-ions at energies above the Coulomb barrier
Transfer of nucleons – trend to equilize N/Z ratio
Population of Yrast states in final fragments
Thick target experimentsThick target experiments
R. Broda et al., JPG 32, 151 (2006)
W. Królas et al., NPA 724, 289 (2003)
Fragments stopped in the target, no isotopic identification
Aquisition of high statistics - coincidence data sets
Level structure from coincidence analysis, ID from cross-coincidences and/or known transitions
GAMMASPHERE
R.Broda et al., Phys.Rev. Lett. 74, 868 (95)
5-
-
4+
2+
(2+)
0+
70Ni4272Ni44
1.261.10
1114
(4+, 3-)
(5-)
-ray thick target measurements with DIC
advantages Gamma rays from all reaction products
Gamma rays from the stopped nuclei – narrow lines – easy analysis of coincidences
Detection of cross-coincidences – some potential for identification
CLARAPRISMA
~ advantages
~ limitations
limitations
Gamma spectra very complicated(hundreds of sources)
Gamma rays from the short lived states smeared out by the Doppler effect (emitted before a product is stopped)
Difficulties of identifications withouta starting point.
Angular distribution of rays almost isotropic
andGASP88
PRISMA spectrometerPRISMA spectrometer A magnetic heavy ion
spectrometer designed to fully identify (A, Z) fragments deflected at large angles
CLARA: an array of 24 Clover detectors
238U + 330 MeV 48Ca
Complementary sets of data: PRISMA – (A,Z) identification, fast transitionsand GAMMASPHERE – -coincidence data
0
2
4
(4 )
(5 )
(7 )
(5 )+
-
(5 )-
-
-
+
-
+
+
1 0 2 7
2 9 7 13 4 8 8
0
1 0 2 6 .8
3 9 9 7 .4
4 8 3 0 .8
4 5 1 5 .3
5 1 4 7 .65 5 1 7 .3
6 8 7 0 .1
1 76 01 35 3
1 0 88
8 33
5 18
4 07 4 325 11 0 .15 0 8 5 .0(4 )-
6 32
1 00 2
5 95
111 3
1 51 9
Ca5020 30
2+
Evolution of Nuclear Structure with Evolution of Nuclear Structure with the Increase of Neutron Richnessthe Increase of Neutron Richness
Changes in shell structure – rearrangements of orbitals
Vanishing of shell gaps, appearance of new „magic numbers”
Experimental evidence needed
Experimental challenge – nuclei not easily accessible
Shell model description Shell model description of neutron-rich Potassium isotopesof neutron-rich Potassium isotopes
48Ca double closed-shell configuration
For Potassium (Z=19): a proton-hole, nearest shells are s1/2, d3/2 and d5/2
For neutron-rich (N > 28): neutrons in p3/2, p1/2 and/or f5/2
shells
Evidence of a 7/2Evidence of a 7/2–– isomer in isomer in 4747KK
(7/2 )-
3511
655
3152
2147
4433
3339
1094
267
1319
2020
360 3/2 +
0 +
1660
360
1/2
4166
K4719 28
1660 M2
1/2+
3/2+
1660 keV line not in prompt gamma spectrum, assigned as an M2 isomeric transition: 7/2–
3/2+
7/2– isomer,T1/2 = 7 ns
(7/2 )-
3511
655
3152
2147
4433
3339
1094
267
1319
2020
360 3/2 +
0 +
1660
360
1/2
4166
K4719 28
7ns
M2
Shell model configurations in Shell model configurations in 4848KK
47K28
πs1/2–1
πd3/2–1
πf7/2
+ νp3/2
1–2–
2–
0–
1–3–
4+3+
2+
5+
48K29
πf7/2 υp3/2
πs1/2 –1
υp3/2
πd3/2–1
υp3/2
First experimental identification First experimental identification of excited states in of excited states in 4848KK
PRISMA
GAMMASPHERE
Identification of 48K gamma lines from PRISMA
Level scheme established from GAMMASPHERE coincidence data
New 6.5 ns isomer placed in 48K
First observation of excited states in First observation of excited states in 4949KK
Gamma lines identified from PRISMA Level scheme from coincidence analysis
πf7/2
πs1/2–1
πd3/2–1
PRISMA
Energies of lowest Energies of lowest 1/21/2++, , 3/23/2++ andand 7/27/2––
states in odd K isotopesstates in odd K isotopes
2814
1/2+
MeV
2
1
0
360
7713/2+
2522
980
561474
1294
738
1081
20202107
7/2–
39K2041K22
43K2445K26
47K2849K30
exc
itatio
n e
ne
rgy
Evolution of relative Evolution of relative ππss1/21/2–1–1 andand ππdd3/23/2
–1 –1
pproton single particle energiesroton single particle energies
As neutrons occupy the f7/2 orbital, proton orbitals are shifted – interaction f7/2 ↔ d3/2 is attractive, f7/2 ↔ s1/2 is repulsive
πs1/2–1
πd3/2–1
MeV1
0
-1
-2
-3
N=20 22
3028
2624
This behaviour consistent with the predicted monopole effect of the tensor force
KrakKraków group and collaboratorsów group and collaborators
R. Broda, B. Fornal, W. Królas, T. Pawłat, J. Wrzesiński IFJ PAN Kraków
S. Lunardi, A. Gadea, N. Marginean, L. Corradi, A.M. Stefanini, F. Scarlassara, G. Montagnoli, M. Trotta, D. Napoli, E. Farnea Laboratori Nazionali di Legnaro and INFN Padova
R.V.F. Janssens, M.P. Carpenter, T. Lauritsen, D. Seweryniak, S. Zhu Argonne National Laboratory
New experimental openingNew experimental opening
Thick target data insufficient:difficult isotopic identification,fast gamma transitions unobserved
PRISMA spectrometer designed for identification of deep-inelastic reaction fragments
PRISMA