611 research outputs found
coupling determined beyond the chiral limit
Within the conventional QCD sum rules, we calculate the coupling
constant, , beyond the chiral limit using two-point correlation
function with a pion. We consider the Dirac structure, , at
order, which has clear dependence on the PS and PV coupling schemes
for the pion-nucleon interactions. For a consistent treatment of the sum rule,
we include the linear terms in quark mass as they constitute the same chiral
order as . Using the PS coupling scheme for the pion-nucleon
interaction, we obtain , which is very close to the
empirical coupling. This demonstrates that going beyond the chiral
limit is crucial in determining the coupling and the pseudoscalar coupling
scheme is preferable from the QCD point of view.Comment: 8 pages, revtex, some errors are corrected, substantially revise
Identification and rejection of scattered neutrons in AGATA
Gamma rays and neutrons, emitted following spontaneous fission of 252Cf, were
measured in an AGATA experiment performed at INFN Laboratori Nazionali di
Legnaro in Italy. The setup consisted of four AGATA triple cluster detectors
(12 36-fold segmented high-purity germanium crystals), placed at a distance of
50 cm from the source, and 16 HELENA BaF2 detectors. The aim of the experiment
was to study the interaction of neutrons in the segmented high-purity germanium
detectors of AGATA and to investigate the possibility to discriminate neutrons
and gamma rays with the gamma-ray tracking technique. The BaF2 detectors were
used for a time-of-flight measurement, which gave an independent discrimination
of neutrons and gamma rays and which was used to optimise the gamma-ray
tracking-based neutron rejection methods. It was found that standard gamma-ray
tracking, without any additional neutron rejection features, eliminates
effectively most of the interaction points due to recoiling Ge nuclei after
elastic scattering of neutrons. Standard tracking rejects also a significant
amount of the events due to inelastic scattering of neutrons in the germanium
crystals. Further enhancements of the neutron rejection was obtained by setting
conditions on the following quantities, which were evaluated for each event by
the tracking algorithm: energy of the first and second interaction point,
difference in the calculated incoming direction of the gamma ray,
figure-of-merit value. The experimental results of tracking with neutron
rejection agree rather well with Geant4 simulations
Band termination in the N=Z Odd-Odd Nucleus 46V
High spin states in the odd-odd N=Z nucleus 46V have been identified. At low
spin, the T=1 isobaric analogue states of 46Ti are established up to I = 6+.
Other high spin states, including the band terminating state, are tentatively
assigned to the same T=1 band. The T=0 band built on the low-lying 3+ isomer is
observed up to the 1f7/2-shell termination at I=15. Both signatures of a
negative parity T=0 band are observed up to the terminating states at I = 16-
and I = 17-, respectively. The structure of this band is interpreted as a
particle-hole excitation from the 1d3/2 shell. Spherical shell model
calculations are found to be in excellent agreement with the experimental
results.Comment: 5 pages, 4 figure
Transition probabilities in the X(5) candidate Ba
To investigate the possible X(5) character of 122Ba, suggested by the ground
state band energy pattern, the lifetimes of the lowest yrast states of 122Ba
have been measured, via the Recoil Distance Doppler-Shift method. The relevant
levels have been populated by using the 108Cd(16O,2n)122Ba and the
112Sn(13C,3n)122Ba reactions. The B(E2) values deduced in the present work are
compared to the predictions of the X(5) model and to calculations performed in
the framework of the IBA-1 and IBA-2 models
Strong Deformation Effects in Hot Rotating 46Ti
Exotic-deformation effects in 46Ti nucleus were investigated by analysing the
high-energy gamma-ray and the alpha-particle energy spectra. One of the
experiments was performed using the charged-particle multi-detector array ICARE
together with a large volume (4"x4") BGO detector. The study focused on
simultaneous measurement of light charged particles and gamma-rays in
coincidence with the evaporation residues. The experimental data show a
signature of very large deformations of the compound nucleus in the Jacobi
transition region at the highest spins. These results are compared to data from
previous experiments performed with the HECTOR array coupled to the EUROBALL
array, where it was found that the GDR strength function is highly fragmented,
strongly indicating a presence of nuclei with very large deformation.Comment: 10 pages, 6 figures, Proceedings of the Zakopane Conference on
Nuclear Physics, to be published in Acta Phys. Pol. B (2007
High-spin states and band terminations in v 49
High-spin states in 49 V have been studied through the 28 Si(28 Si, α3p) reaction using the EUROBALL Îł-ray detector array. The 49 V level scheme has been extended up to 13.1 MeV including 21 new states. Both negative and positive parity states have been interpreted in the framework of theShell Model. The 27/2â and the 31/2+ band termination states have been observed in agreement with theoretical predictions.Fil: Rodrigues Ferreira Maltez, Dario Pablo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de InvestigaciĂłn y Aplicaciones No Nucleares. Gerencia FĂsica (Centro AtĂłmico Constituyentes). Proyecto Tandar; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de FĂsica; ArgentinaFil: Hojman, Daniel Leonardo. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de InvestigaciĂłn y Aplicaciones No Nucleares. Gerencia FĂsica (Centro AtĂłmico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Lenzi, Silvia M.. Istituto Nazionale Di Fisica Nucleare.; Italia. UniversitĂ di Padova; ItaliaFil: Cardona, Maria Angelica. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de InvestigaciĂłn y Aplicaciones No Nucleares. Gerencia FĂsica (Centro AtĂłmico Constituyentes). Proyecto Tandar; Argentina. Universidad Nacional de San MartĂn. Escuela de Ciencia y TecnologĂa; ArgentinaFil: Fernea, Enrico. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Axiotis, M.. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Beck, C.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Bednarczyk, P.. Polish Academy of Sciences; ArgentinaFil: Bizzetti, P. G.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Bizzetti Sona, A. M.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Della Vedova, F.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Grebosz, J.. Polish Academy of Sciences; ArgentinaFil: Haas, F.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Kmiecik, M.. Polish Academy of Sciences; ArgentinaFil: Maj, A.. Polish Academy of Sciences; ArgentinaFil: MÄczyĆski, W.. Polish Academy of Sciences; ArgentinaFil: Napoli, D. R.. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Nespolo, M.. UniversitĂ di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Papka, P.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: SĂĄnchez i Zafra, A.. UniversitĂ© de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Styczen, J.. Polish Academy of Sciences; ArgentinaFil: Thummerer, S.. Alfred-Wegener-Institut, Helmholtz-Zentrum fĂŒr Polar- und Meeresforschung; AlemaniaFil: ZiÄbliĆski, M.. Polish Academy of Sciences; Argentin
Very high rotational frequencies and band termination in 73Br
Rotational bands in 73Br have been investigated up to spins of 65/2 using the
EUROBALL III spectrometer. One of the negative-parity bands displays the
highest rotational frequency 1.85 MeV reported to date in nuclei with mass
number greater than 25. At high frequencies, the experimental dynamic moment of
inertia for all bands decrease to very low values, indicating a loss of
collectivity. The bands are described in the configuration-dependent cranked
Nilsson-Strutinsky model. The calculations indicate that one of the
negative-parity bands is observed up to its terminating single-particle state
at spin 63/2. This result establishes the first band termination case in the A
= 70 mass region.Comment: 6 pages, 6 figures, submitted to Phys. Rev. C as a Rapid
Communicatio
Transition rates and nuclear structure changes in mirror nuclei 47Cr and 47V
Lifetime measurements in the mirror nuclei 47Cr and 47V were performed by
means of the Doppler-shift attenuation method using the multidetector array
EUROBALL, in conjunction with the ancillary detectors ISIS and the Neutron
Wall. The determined transition strengths in the yrast cascades are well
described by full pf shell model calculations.Comment: Latex2e, 11 pages, 3 figure
Spectroscopic studies of Dy-168,170 using CLARA and PRISMA
Preliminary results from an experiment aiming at Dy-170. Submitted to the LNL
Annual Report 2008.Comment: 2 pages, 4 figures, Submitted to the LNL Annual Report 200
Excited bands and signature dependent electromagnetic decay properties in neutron-rich 159,161,163Dy
14 pĂĄgs.; 12 figs.; 3 tabs. ; PACS number(s): 23.20.Lv, 27.70.1q, 21.10.ReHigh-spin states of the neutron-rich odd nuclei 159,161,163Dy have been studied using the incomplete fusion reactions 158,160Gd(7Li,(p,d,t)xn). In 159Dy, the band crossing in the 11/2-[505] band has been observed for the first time. Moreover, 11 E1 transitions connecting both signatures of the 3/2-[521] band to the 5/2+[642] band have been observed in this nucleus; the deduced B(E1)/B(E2) ratios as well as the B(M1)/B(E2) ratios for transitions within the 3/2-[521] band show a pronounced signature dependence. In 161Dy and 163Dy, rotational bands have been extended to significantly higher spin values. In 161Dy, the sequences built on the neutron 5/2-[523] and 3/2-[521] states have been followed up to spin 49/2- and 33/2-, respectively, and in both cases upbends have been observed around hâ Ï â0.26 MeV. In addition, a new band most probably built on the 11/2-[505] single-particle state has been identified in this isotope. In 163Dy, both the 5/2-[523] ground state band and the structure built on the 5/2+[642] neutron orbit have been extended up to the 45/2- and 49/2+ states, respectively. However, no band crossing has been observed in this nucleus. The properties of the observed bands in 159,161,163Dy are discussed and compared to calculations performed within the projected shell model. ©2003 The American Physical SocietyThis work was supported by the Deutsches Bundesministerium
fĂŒr Bildung, Wissenschaft, Forschung und Technologie
(BMBF). A.J. acknowledges support by the Deutsche Forschungsgemeinschaft
(DFG) within the Heisenberg program.Peer Reviewe
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