排序方式: 共有14条查询结果,搜索用时 15 毫秒
1.
Brodowski W Bilger R Calén H Clement H Ekström C Fransson K Greiff J Häggström S Höistad B Johanson J Johansson A Johansson T Kilian K Kullander S Kupść A Marciniewski P Morosov B Oelert W Pätzold J Ruber RJ Schepkin M Scobel W Seluzhenkov I Stepaniak J Sukhanov A Turowiecki A Wagner GJ Wilhelmi Z Zabierowski J Zlomanczuk J 《Physical review letters》2002,88(19):192301
The pp-->pp pi(+) pi(-) reaction has been measured exclusively near threshold at CELSIUS. The total cross sections are nearly an order of magnitude lower than expected from previous inclusive measurements. The differential cross sections reveal pp-->pp(*)(1440)-->pp sigma = pp(pi(+)pi(-))(I = l = 0) as the dominant process as well as significant contributions from p(*)-->Delta(++)pi(-)-->psigma. The observed anisotropy in the proton angular dependence is consistent with heavy-meson exchange. In the invariant mass spectra, no narrow structures of statistical relevance (3sigma) are found. 相似文献
2.
M.A. Nasser M.M. Gazzaly J.V. Geaga B. Höistad G. Igo J.B. McClelland A.L. Sagle H. Spinka J.B. Carroll V. Perez-Mendez E.T.B. Whipple 《Nuclear Physics A》1978,312(3):209-216
The p-4He elastic differential cross section has been measured at a kinetic energy of 2.68 GeV. The momentum transfer region studied is t = 0.15–0.66 (GeV/c)2. The cross section displays a shallow first minimum and shape very similar to recent data at 1 GeV. 相似文献
3.
A magnetic spectrometer was used for the momentum analysis of pions produced by 185 MeV protons on a 9Be target. The obtained energy resolution (0.55 MeV FWHM) made it possible to resolve a number of discrete final states in 10Be and 10C. Energy spectra were measured in the angular region 15°–130° (lab). Angular distributions for six peaks in 10Be and four peaks in 10C are presented in tables and graphs. A peak corresponding to a not previously reported level in 10Be was observed at 11.75 ±0.11 MeV excitation energy. The measured ratio for the ground state analogues was found to be angular dependent and varied from 30 at 35° (lab) to 2 at 125° (lab). The results are compared with theoretical predictions and discussed in terms of one- and two-nucleon models. 相似文献
4.
The reactions and have been studied for proton energies between 163 and 186 MeV. Angular distributions for the ground states and the excited state at 2.13 MeV in 11B are presented. Cross sections calculated in the one-nucleon model, under different assumptions about the interaction Hamiltonian as well as the pion and proton optical potentials, are compared with the experimental distribution from the state in 41Ca. 相似文献
5.
H. Clement M. Bashkanov D. Bogoslawsky F. Cappellaro E. Doroshkevich C. Ekström L. Geren B. Höistad M. Jacewicz T. Johansson O. Khakimova I. Koch S. Kullander A. Kuznetsov P. Marciniewski B. Morosov H. Petterson A. Povtorejko K. Schönning B. Shwartz V. Sopov P.-E. Tegner V. Tikhomirov M. Wolke J. Zabierowski J. Z?omanczuk for the CELSIUS-WASA Collaboration 《Progress in Particle and Nuclear Physics》2008,61(1):276-282
The ABC effect-an intriguing low-mass enhancement in the ππ invariant mass spectrum-is known from inclusive measurements of two-pion production in nuclear fusion reactions. First exclusive measurements carried out at CELSIUS-WASA for the fusion reactions leading to d or 3He reveal this effect to be a σ-channel phenomenon associated with the formation of a ΔΔ system in the intermediate state and combined with a resonance-like behavior in the total cross-section. Together with the observation that the differential distributions do not change in shape over the resonance region the features fulfill the criteria of an isoscalar s-channel resonance in pn and NNππ systems, if the two emitted nucleons are bound. It obviously is robust enough to survive in nuclei as a dibaryonic resonance configuration. In this context also the phenomenon of NΔ resonances is reexamined. 相似文献
6.
Chr. Bargholtz B. A. Chernyshev L. Gerén V. N. Grebenev Yu. B. Guro B. Höistad I. V. Laukhin K. Lindberg V. G. Sandukovsky R. R. Shafigullin P. -E. Tegnér 《Physics of Atomic Nuclei》2005,68(3):488-490
A search for deeply bound pionic states of xenon produced in the 136Xe(d, 3He)135Xeπ-bound reaction at E d = 500 MeV is reported. The population of the 1s pionic-atom state of 135Xe is observed on the predicted level of the cross section ~ 40 μb/sr. The binding energy of the 1s state, B = 2.9 ± 0.5 MeV, however, is lower than theoretically predicted. 相似文献
7.
T. Skorodko M. Bashkanov D. Bogoslawsky H. Calén H. Clement E. Doroshkevich L. Demiroers C. Ekström K. Fransson L. Gustafsson B. Höistad G. Ivanov M. Jacewicz E. Jiganov T. Johansson O. Khakimova S. Keleta I. Koch F. Kren S. Kullander A. Kup?? P. Marciniewski R. Meier B. Morosov C. Pauly H. Petrén Y. Petukhov A. Povtorejko R.J.M.Y. Ruber K. Schönning W. Scobel B. Shwartz J. Stepaniak P. Thörngren-Engblom V. Tikhomirov G.J. Wagner M. Wolke A. Yamamoto J. Zabierowski J. Zlomanczuk 《Physics letters. [Part B]》2009
8.
T. Skorodko M. Bashkanov D. Bogoslawsky H. Calen F. Cappellaro H. Clement L. Demiroers E. Doroshkevich D. Duniec C. Ekström K. Franssen L. Gustafsson B. Höistad G. Ivanov M. Jacewicz E. Jiganov T. Johansson O. Khakimova M. Kaskulov S. Keleta I. Koch F. Kren S. Kullander A. Kupść A. Kuznetsov P. Marciniewski R. Meier B. Morosov C. Pauly H. Petterson Y. Petukhov A. Povtorejko K. Schönning W. Scobel B. Shwartz V. Sopov J. Stepeniak P. Thörngren-Engblom V. Tikhomirov G. J. Wagner M. Wolke A. Yamamoto J. Zabierowski J. Złomanczuk 《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):317-319
In most investigations the Roper resonance is sensed only very indirectly via complex partial-wave analyses. We find indications
for its excitation in the invariant nπ+ mass spectrum of the pp → npπ+ reaction at M ≈ 1360 MeV with a width of ≈ 150 MeV . The values fit very favorably to the most recent phase shift results as well as to
the observations at BES. In the near-threshold two-pion production pp → ppπ0π0 , where the Roper excitation and its subsequent decays via the routes N
* → Δπ → Nππ and N
* → Nσ are the only dominant processes, we find its direct decay into the Nσ channel to be the by far dominating decay process --in favor of a monopole excitation of the Roper resonance. 相似文献
9.
K. Sch?nning Chr. Bargholtz M. Bashkanov M. Berlowski D. Bogoslawsky H. Calén H. Clement L. Demir?rs C. Ekstr?m K. Fransson L. Gerén L. Gustafsson B. H?istad G. Ivanov M. Jacewicz E. Jiganov T. Johansson S. Keleta O. Khakimova F. Kren S. Kullander A. Kupsc A. Kuzmin K. Lindberg P. Marciniewski B. Morosov W. Oelert C. Pauly H. Petrén Y. Petukhov A. Povtorejko W. Scobel R. Shafigullin B. Shwartz T. Skorodko V. Sopov J. Stepaniak P. -E. Tegnér P. Th?rngren Engblom V. Tikhomirov A. Turowiecki G. J. Wagner M. Wolke J. Zabierowski I. Zartova J. Z?omanczuk 《The European Physical Journal A - Hadrons and Nuclei》2010,45(1):11-21
10.
S. Dahlgren D. Hasselgren B. H istad A. Ingemarsson A. Johansson P. -U. Renberg O. Sundberg G. Tibell 《Nuclear Physics A》1967,90(3):673-695
A magnetic spectrometer was used for the energy analysis of protons scattered from targets of magnesium (natural isotopic composition) and aluminium. The mean energy of the incident protons in the targets was 185 MeV. A total energy resolution of 350 keV (FWHM) was achieved, which made possible the observation of the excitation of a large number of discrete levels. Energy spectra were measured in the angular region of 4° to 40° (lab system).
The results are presented partly in the form of tables giving measured excitation energies and maximum cross sections for resolved levels and partly in the form of graphs of angular distributions of the differential cross sections.
A qualitative discussion of the results is given in terms of the multipolarities of the transitions involved and comparisons are made with similar results from other experiments in inelastic scattering and in a few cases with theoretical predictions. 相似文献