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1.
Isomeric states in 210-215Ra have been populated by the decay of the compound nuclei 216,220Ra produced in irradiations of 204,208Pb with 12C at
MeV. Published values for
-ray energies and half-lives were confirmed for
Ra. Our data for
Ra agree with the
-energies and the half-life measured at the RITU separator, University of Jyväskylä (Finland). Its decay pattern is complex. Two series of
-rays of
keV and
keV were observed. A half-life of
s was measured. The isomeric state is attributed to an 8 + state at E
* = 2053.8keV. A previously unknown isomeric state was assigned to
Ra. It has a half-life of (
)
and it decays by emission of
-rays with energies of 396.1keV and 802.0keV. It is attributed to a 13/2 + state at E
* = 1198.1 keV.PACS:
23.60. + e
decay - 27.90. + b
相似文献
2.
J. G. Messchendorp 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):417-419
Preliminary differential cross-sections of the reactions
and
with A = 1
H, 12
C, and
nat
Pb are presented. A significant nuclear-mass dependence of the
invariant-mass distribution is found in the
channel. The dependence is not observed in the
channel. The in-medium observation in the
channel is consistent with an in-medium modification of the
interaction in the I = J = 0 channel, changing width and pole position of a
resonant state.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.60.Le Meson production - 21.65. + f Nuclear matterJ.G. Messchendorp: For the TAPS and A2 Collaborations 相似文献
3.
M. J. Vicente Vacas 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):479-481
The
interaction in the scalar isoscalar channel is studied as a function of the baryonic density in the framework of a chiral unitary approach which successfully reproduces vacuum
-
phase shifts. We present some results on the
-meson pole, which is generated dynamically in our model, in nuclear matter. Finally, we analyze the (
) reaction on nucleons and nuclei in the kinematical region where the scalar isoscalar
scattering amplitude is influenced by the low mass of the
in nuclei, and thus, presents a large enhancement close to the position of its pole. Indeed, we find, that the final-state interaction of the pions modified by the nuclear medium produces a large shift of strength of the two-pion invariant-mass distribution in the (
) channel consistent with recent experimental data.Received: 30 September 2002, Published online: 22 October 2003PACS:
14.40.-n Properties of specific particles: Mesons - 25.20.-x Photonuclear reactions - 21.65. + f Nuclear matter 相似文献
4.
A. Sibirtsev 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):475-478
We investigate the
decay width of excited charmonium states at finite nuclear density with simultaneous modification of both D- and
-mesons in nuclear matter. The strongest effect is found for the
-meson. The medium modification can be detected by dilepton spectroscopy as substantial
broadening and anomalous
absorption.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.25.Gv Decays of
,
, and other quarkonia - 14.40.Lb Charmed mesons - 14.65.Dw Charmed quarks - 24.85. + p Quarks, gluons, and QCD in nuclei and nuclear processes 相似文献
5.
A. M. Gasparyan V. Yu Grishina L. A. Kondratyuk W. Cassing 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):305-307
Using the Quark-Gluon Strings Model (QGSM) combined with Regge phenomenology we consider the reactions
and
which are dominated by the contributions of the K
* and D
* Regge trajectories, respectively. The spin structure of the amplitudes is described by introducing Reggeized Born terms. It is found that the existing data for the reaction
are in reasonable agreement with the model predictions. To describe the absolute values of the cross-sections it is necessary to introduce also suppression factors which can be related to absorption corrections. Furthermore, assuming the SU(4) symmetry to hold for Regge residues and the universality of absorption corrections we calculate the cross-section of the reaction
. Employing the latter results from
reactions we then estimate the contributions of the pion exchange mechanism to the cross-sections of the reactions
and
and compare them with the contributions of the K and D exchanges. We find that the NN reactions are dominated not by pion exchange but by K and D exchanges, respectively. Moreover, assuming the SU(4) symmetry to hold approximately for the coupling constants
=
we analyze also the production of leading
-hyperons in the reaction
. It is shown that the non-perturbative mechanism should give an essential contribution to the
yield for
.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.85.Fb Inelastic scattering: two-particle final states - 13.85.Hd Inelastic scattering: many-particle final states - 14.20.Lq Charmed baryons - 14.40.Lb Charmed mesons 相似文献
6.
The nuclear system at the limit of excitation energy and angular momentum is here studied in the case of the superdeformed nucleus 143Eu using
-spectroscopy techniques. The data are based on a EUROBALL experiment using the reaction 37Cl + 110Pd
Eu + 4n. The influence of thermal energy on superdeformed configurations is investigated through the analysis of the quasi-continuum spectra formed by E2 transitions among states of excited rotational bands with energy extending up to 4-5 MeV above the yrast line. In particular, the effective lifetimes of the discrete rotational bands forming ridge structures in
-
coincidence matrices is measured by a Doppler Shift Attenuation Method. The deduced quadrupole deformation of
10 eb indicates that the nucleus maintains its collectivity with increasing excitation energy, supporting the superdeformed character of the excited nuclear rotation. The obtained number of superdeformed discrete bands forming the ridge structures is found in good agreement with microscopic cranked shell model calculations including the decay-out process into the lower deformation minimum. In addition, the nuclear properties at higher excitation energies are investigated through the E1
-decay of the giant dipole resonance (GDR). It is found that the intensity of the superdeformed yrast and excited bands increases by a factor of approximately 1.6 when a coincidence with a high-energy
-ray is required, showing the importance of the E1 cooling in the feeding mechanism of the superdeformed states.Received: 2 December 2002, Published online: 2 March 2004PACS:
21.10.Tg Lifetimes - 21.10.Re Collective levels - 23.20.Lv
transitions and level energies - 27.60. + j
相似文献
7.
M. Stanoiu F. Azaiez F. Becker M. Belleguic C. Borcea C. Bourgeois B. A. Brown Z. Dlouhý Z. Dombrádi Z. Fülöp H. Grawe S. Grévy F. Ibrahim A. Kerek A. Krasznahorkay M. Lewitowicz S. Lukyanov H. van der Marel P. Mayet J. Mrázek S. Mandal D. Guillemaud-Mueller F. Negoita Y. E. Penionzhkevich Z. Podolyák P. Roussel-Chomaz M. G. Saint Laurent H. Savajols O. Sorlin G. Sletten D. Sohler J. Timár C. Timis A. Yamamoto 《The European Physical Journal A - Hadrons and Nuclei》2003,20(1):95-96
We have studied the structure of light neutron-rich nuclei around N = 16 by employing the in-beam
-ray spectroscopy technique using the fragmentation of secondary beams of 25,26Ne, 27,28Na and 29,30Mg isotopes. This secondary-beam cocktail was obtained by the fragmentation of a 36S beam at 77.5 MeV
by the SISSI/GANIL facility. By a second-step fragmentation, we have measured
-ray-residue coincidences in 17-20C and 23,24O and described the obtained levels in the framework of the shell model.Received: 31 October 2002, Published online: 24 February 2004PACS:
23.20.Lv
transitions and level energies - 21.60.Cs Shell model - 27.20. + n
- 27.30. + t
相似文献
8.
A short summary of the present status of prompt particle decays in the mass
region is presented. It includes recent results from a GAMMASPHERE experiment, which aimed at the combined high-resolution spectroscopy of light charged particles and
-rays to allow for more detailed studies of known decays and the identification of new cases of discrete prompt proton and
-particle emission from highly and superdeformed states.Received: 10 October 2002, Published online: 17 February 2004PACS:
23.50. + z Decay by proton emission - 23.60. + e
decay - 27.40. + z
- 27.50. + e
相似文献
9.
Gyürky Gy. Fülöp Zs. Somorjai E. Kiss G. Rolfs C. 《The European Physical Journal A - Hadrons and Nuclei》2004,20(2):355-358
The absolute strengths of the
keV resonance in the
reaction and of the
keV resonance in the
reaction have been measured to
meV and
meV, respectively, in good agreement with previous values. These resonances can be used to measure the absolute acceptance of the recoil separator ERNA to a precision of about 10%.Received: 12 December 2003, Revised: 10 February 2004, Published online: 3 August 2004PACS:
24.30.-v Resonance reactions - 25.40.Lw Radiative capture - 26.20. + f Hydrostatic stellar nucleosynthesis 相似文献
10.
V. R. Brown B. F. Gibson J. A. Carlson R. Schiavilla 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):289-291
The parity-non-conserving longitudinal asymmetry in proton-proton (p
p) elastic scattering is calculated in the lab energy range 0-350 MeV using contemporary, realistic strong-interaction potentials combined with a weak-interaction potential comprised of
- and
-meson exchanges as exemplified by the DDH model. Values for the
- and
-meson coupling constants,
and
, are determined from comparison with the measured asymmetries at 13.6 MeV, 45 MeV, and 221 MeV.Received: 30 September 2002, Published online: 22 October 2003PACS:
21.30.-x Nuclear forces - 24.80. + y Nuclear tests of fundamental interactions and symmetries - 25.40.Cm Elastic proton scattering 相似文献
11.
Ts Venkova R. M. Lieder W. Gast D. Bazzacco G. de Angelis E. Podsvirova H. M. Jäger L. Mihailescu R. Menegazzo S. Lunardi C. Rossi Alvarez C. Ur T. Martinez M. Axiotis D. Napoli W. Urban T. Rzaca-Urban 《The European Physical Journal A - Hadrons and Nuclei》2003,18(4):577-581
High-spin states in the odd-proton nucleus 173Lu have been populated in a 170Er(7Li,4n) reaction and the emitted
-radiation was detected with the GASP array. The favoured and unfavoured sequences of the
band have been considerably extended. The favoured sequence does not show any indication of a band crossing up to a rotational frequency of
0.45 MeV. This is the largest crossing frequency ever observed for 1/2- [541] bands of odd-proton nuclei with
and
. Previous Cranked Shell Model (CSM) calculations underestimate the crossing frequency by 100 keV.Received: 19 May 2003, Published online: 11 November 2003PACS:
21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Re Collective levels - 23.20.Lv
transitions and level energies - 27.70. + q
相似文献
12.
The
-decay of 149Ba to 149La has been investigated by means of
- and X-ray spectroscopy, and a partial level scheme of 149La has been constructed for the first time. It includes thirteen
-rays and ten excited states. The exotic 149La is the heaviest lanthanum for which spectroscopic information is now available. We have applied the shell correction approach with the axially deformed Woods-Saxon potential in order to calculate the deformation energy for the 149La ground state. The deformed ground state was found at
0.23,
0 and
0.12.Received: 18 July 2003, Revised: 12 January 2004, Published online: 26 May 2004PACS:
27.60. + j
- 29.30.Kv X- and
-ray spectroscopy 相似文献
13.
A. N. Andreyev D. Ackermann F. P. Heßberger S. Hofmann M. Huyse I. Kojouharov B. Kindler B. Lommel G. Münzenberg R. D. Page K. Van de Vel P. Van Duppen K. Heyde 《The European Physical Journal A - Hadrons and Nuclei》2003,18(1):55-64
Alpha-decay of the new nuclide 184Bi has been studied in the complete-fusion reaction 93Nb(94Mo, 3n)184Bi at the velocity filter SHIP. The evaporation residues were separated in-flight and subsequently identified on the basis of recoil-
, recoil-
-
analysis and excitation functions measurements. Two
-decaying isomeric states in 184Bi with half-life values of 13(2) ms and 6.6(1.5) ms were identified. The
-branching ratio of 180Tl was deduced for the first time as
. Improved data on the fine-structure
-decay of 186Bi were obtained in the 93Nb(95Mo, 2n)186Bi reaction. A similarity of the decay energies and half-life values of 184,186Bi is pointed out and a possible explanation for this effect is suggested.Received: 14 March 2003, Revised: 29 April 2003, Published online: 2 September 2003PACS:
23.60.+e
decay - 27.70.+q
- 27.80.+w
K. Heyde: Present address: EP-ISOLDE, CERN, CH-1211, Geneva 23, Switzerland. 相似文献
14.
The laser ion source has been used for the study of the isotope shifts of neutron-deficient Eu isotopes. The extension of the region of applicability of the method by using the
- and
-radiation detection is reported. We have measured the isotope shifts of the europium optical line 576.520 nm for
. To increase the laser ion source efficiency an axial magnetic field (350 gauss) was applied. Nearly a twofold rise of the ionization efficiency for Eu was observed. By using the effect of optical ion bunching an increase of the selectivity was obtained. The isotope shift data for
are in agreement with the previously measured isotope shifts for these nuclides. The new data for
and refined data for
point to a gradual increase of the deformation for these isotopes. Comparisons with microscopic-macroscopic calculations and calculations in the framework of the Hartree-Fock model were performed.Received: 10 November 2003, Revised: 28 April 2004, Published online: 19 October 2004PACS:
29.25.Rm Sources of radioactive nuclei - 42.62.Fi Laser spectroscopy - 21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Ft Charge distribution 相似文献
15.
C. N. Papanicolas 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):141-145
The conjectured deformation of hadrons and its experimental verification offer a particularly fertile ground for understanding the intricate dynamics of their constituents and QCD at the confiment scale. The detailed study of the
transition is viewed as the preferred method of experimental investigation of this central issue in hadronic physics. A brief overview of the field is presented, followed by a presentation of the most recent results from Bates
program. The new Bates/OOPS data at Q
2 = 0.127 GeV/c
2) yield
and
and they exclude a spherical nucleon and/or
. The magnitude and the origin of the deformation is the focus of the ongoing and planned investigations.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.60.Le Meson production - 13.88. + e Polarization in interactions and scattering - 13.40.Gp Electromagnetic form factors - 14.20.Gk Baryon resonances with S = 0C.N. Papanicolas: Invited plenary talk 相似文献
16.
W. Cassing 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):467-470
The production and decay of vector mesons (
) in pA and AA reactions is studied with particular emphasis on their in-medium spectral functions. It is explored within transport calculations if hadronic in-medium decays like
or
might provide complementary information to their dilepton (e
+
e
-) decays. Whereas the
signal from the
-meson is found to be strongly distorted by pion rescattering, the
-meson Dalitz decay to
appears promising even for more heavy nuclei in
and pA reactions. Furthermore, the influence of nucleon and kaon/antikaon potentials on the
yields and spectra in pA collisions is calculated and compared to the recent data from the ANKE Collaboration.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.60.Le Meson production - 13.75.Jz Kaon-baryon interactions - 14.40.Aq
, K, and
mesons - 25.40.-h Nucleon-induced reactionsW. Cassing: In collaboration with E.L. Bratkovskaya, M. Büscher, Ye.S. Golubeva, V. Grishina, V. Hejny, V. Metag, J. Messchendorp, B. Kamys, L.A. Kondratyuk, P. Kulessa, Z. Rudy, S. Schadmand, A.A. Sibirtsev, H. Ströher 相似文献
17.
Differential cross-sections and proton multiplicities, resulting from the bombardment of 56Fe, 208Pb, and 238U targets by a 190 MeV proton beam were measured for the first time. Data were taken over two different angular ranges 5
-30
and 91
-160
with two different detection systems. Angular distributions of fast (> 20 MeV) protons are all forward peaked, due to the dominating elastic-scattering contribution. Moreover, the shapes of the distributions are quite independent of the target. The results are compared with modern optical-model predictions and with Intra-Nuclear Cascade (INC) calculations. Reasonable agreement between calculations and experimental data is obtained in the forward angles, but the comparison clearly indicates the need to modify the parameterization of the model at backward angles, where the agreement is rather poor.Received: 11 November 2003, Revised: 9 February 2004, Published online: 31 August 2004PACS:
24.10.Ht Optical and diffraction models - 25.40.Ep Inelastic proton scattering - 28.90. + i Other topics in nuclear engineering and nuclear power studies 相似文献
18.
P. Moskal H.-H. Adam A. Budzanowski R. Czyzykiewicz D. Grzonka M. Janusz L. Jarczyk B. Kamys A. Khoukaz K. Kilian P. Kowina T. Lister W. Oelert T. Rozek R. Santo G. Schepers T. Sefzick M. Siemaszko J. Smyrski S. Steltenkamp A. Strzalkowski P. Winter M. Wolke P. Wüstner W. Zipper 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):335-338
The production of
- and
-mesons in elementary nucleon-nucleon collisions has been investigated at the synchrotrons CELSIUS, COSY and SATURNE. The high-quality proton beam with low emittance and small momentum spread permits to study the creation of these mesons very close to the kinematical threshold, where --due to the rapid growth of the phase space volume-- the total cross-section increases by orders of magnitude over a few MeV range of the excess energy. The magnitude and energy dependence of the total cross-section as well as the occupation distribution of the phase space serve as observables for investigating the mechanisms underlying the production processes and the interaction of mesons with nucleons. The precise data on the
and
creation via the
reactions allowed to settle the general features of the
- and
-meson production and revealed the sensitivity of the mentioned observables to the nucleon-nucleon-meson final-state interaction. The particular production properties, like for example, the determination of the dominating exchange processes which lead to the excitation of the S
11 nucleon isobar in the case of
creation, must be established by confrontation with other observables. The present status of this investigation with an emphasis on the results of the COSY-11 Collaboration is briefly presented. The available data are interpreted in view of the production mechanism and the meson-nucleon interaction.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.60.Le Meson production - 13.75.-n Hadron-induced low- and intermediate-energy reactions and scattering (energy
GeV) - 13.85.Lg Total cross sections - 25.40.-h Nucleon-induced reactions 相似文献
19.
G. Martens C. Greiner S. Leupold U. Mosel 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):223-226
We calculate color electric fields of quark/antiquark (
) and 3-quark (qqq) systems within the Chromodielectric Model (CDM). We explicitly evaluate the string tension of flux tubes in the
-system and analyze their profile. To reproduce results of lattice calculations we use a bag pressure
from which an effective strong-coupling constant
follows. With these parameters we get a Y-shaped configuration for large qqq-systems.Received: 30 September 2002, Published online: 22 October 2003PACS:
11.10.Lm Field theory: Nonlinear or nonlocal theories and models - 11.15.Kc Gauge field theories: Classical and semiclassical techniques - 12.39.Ba Phenomenological quark models: Bag model 相似文献
20.
D. Blaschke G. Burau Yu Kalinovsky T. Barnes 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):547-549
We investigate the in-medium modification of pseudoscalar and vector mesons in a QCD-motivated chiral quark model by solving the Dyson-Schwinger equations for quarks and mesons at finite temperature for a wide mass range of meson masses, from light (
,
) to open-charm (D, D
*) states. At the chiral/deconfinement phase transition, the quark-antiquark bound states enter the continuum of unbound states and become broad resonances (hadronic Mott effect). We calculate the in-medium cross-sections for charmonium dissociation due to collisions with light hadrons in a chiral Lagrangian approach, and show that the D- and D
*-meson spectral broadening lowers the threshold for charmonium dissociation by
- and
-mesons. This leads to a step-like enhancement in the reaction rate. We suggest that this mechanism for enhanced charmonium dissociation may be the physical mechanism underlying the anomalous
suppression observed by NA50.Received: 30 September 2002, Published online: 22 October 2003PACS:
05.20.Dd Kinetic theory - 12.38.Mh Quark-gluon plasma - 14.40.-n Mesons - 25.75.Nq Quark deconfinement, quark-gluon plasma production, and phase transitions 相似文献