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1.
High spin states of 57Co have been studied via prompt γ-ray spectroscopy in the reactions 48Ti(12C, p2n) and 54Fe(α, p) at 26–48 MeV and 12–24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable Jπ assignment of , if and , respectively. The previously known level at 2524 keV was assigned to have . These together with the known (1224 keV) and (1690 keV) levels constitute the yrast states of 57Co. The measured lifetimes of the above six levels are (in order of increasing energies) 0.085±0.030, 0.32±0.10, 0.16±0.06, 0.10?0.07+0.06, 1.5?0.54 and 0.17?0.07+0.08 ps, respectively. Comparisons with some theoretical calculations are presented. 相似文献
2.
Three enhancements are observed in the final state ω°π+π+π++π?π? selected from the channel at 715 MeV/c: one in ω°π± at 1040 MeV (~ ≈ 55MeV) ω°π+π?, respectively near 1315 MeV (~ ≈ 100 MeV) and 1405 MeV (~ ≈ 40 MeV). The first two effects are strongly correlated and are interpreted in terms of a sequential decay A°2 through a new object, the B1. The second (ωππ) enhancement seems to be an ?°?° effect below threshold and is attributed to a pionic decay of the effect seen around the same mass in other reactions. 相似文献
3.
P.M. Heinen J.J. Engelen E.W. Kittel W.J. Metzger M.M. Schouten J.S.M. Vergeest R.T. Van De Walle B. Jongejans H. Voorthuis M. Cerrada R.J. Hemingway S.O. Holmgren M.J. Losty 《Nuclear Physics B》1977,122(3):443-463
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states and only. In the 1500 MeV region contributions are observed from the wave decaying into p? and the wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the wave decaying into Δ++π?, the wave decaying into p?, and the wave decaying into p?. 相似文献
4.
B. Niczyporuk T. Zełudziewicz K.W. Chen R. Hartung G. Folger B. Lurz H. Vogel U. Volland H. Wegener J.K. Bienlein R. Graumann J. Krüger M. Leissner M. Schmitz F.H. Heimlich R. Nernst A. Schwarz M. Scheer 《Physics letters. [Part B]》1981,100(1):95-100
We report the first observation of the decay . The 7 events seen yield a branching ratio B(?′→?π+π?)=(19±8)%. A consistent value of B=(26±13)% is obtained from the charged multiplicities of the ?′ and ? decays. Using these values we deduce Γtot(?′)=(31+10?8) keV and Bee(?′)=(1.8±0.5)%. Furthermore we estimate Γ(?′→gg?)=(10±5) keV in agreement with QCD predictions using vector gluons while one would expect 100 keV with scalar gluons. 相似文献
5.
U. Sennhauser L. Felawka T. Kozlowski H.K. Walter F.W. Schlepuetz R. Engfer E.A. Hermes P. Heusi H.P. Isaak H.S. Pruys A. Zglinski W.H.A. Hesselink 《Physics letters. [Part B]》1981,103(6):409-412
A particle unstable state of 4H has been identified in the reaction by observing the two emitted tritons. A resonance energy EΓ=(2.7±0.6) MeV and a reduced width γ2=(2.3±0.6) MeV were deduced, in agreement with the parameters of the ground-state level (Jπ=2?) found in the p-wave of n-t-scattering. The yield per stopped pion is (5.6±1.8)×10?4. Previous measurements in pion absorption are in disagreement with our results. 相似文献
6.
Y. Eisenberg A. Engler B. Haber U. Karshon G. Mikenberg S. Pitluck E.E. Ronat A. Shapira G. Yekutieli 《Physics letters. [Part B]》1974,52(2):239-242
Rare decay modes of the f meson are studied in the final states Δ++π+π?π+π?, Δ++π+π?MM and Δ++π+π?π+π?MM. The ratio is 0.23 ± 0.09 and Γ(f → 4 π) saturates the f inelasticity. A 2 s.d. upper limit of 0.09 is found for the branching ratio . 相似文献
7.
C. Defoix L. Dobrzynski P. Espigat M. Laloum P.Ladrón de Guevara C. Angelini A. Bigi R. Casali R. Pazzi 《Nuclear Physics B》1980,162(1):12-40
An experimental analysis of interactions between the p threshold (√s = 1878 MeV) and √s = 2 100 MeV leads to clear evidence for an s-channel effect in the reaction . A comparison is made with the backward elastic scattering and charge-exchange behaviour. An interpretation in terms of an object strongly coupled to mesonic decay modes, with small or middle-sized elasticity (x ? 0.135?0.06+0.13) is given. No significant narrow structure is observed in the backward elastic scattering between 1.9 and 2 GeV. The experimental resolution of √s in this case is 2 MeV. 相似文献
8.
P. Benkheiri J. Boucrot B. Bouquet P. Briandet B. DAlmagne C.Dang Vu B. Eisenstein A. Ferrer P. Fleury B. Grossetête G. Irwin A. Jacholkowski A. Lahellec H. Nguyen P. Petroff F. Richard P. Rivet G. De Rosny H. Yoshida 《Physics letters. [Part B]》1977,68(5):483-486
From the study of the reaction using a fast proton (pF) trigger device in the CERN Omega spectrometer, we find evidence for two narrow states produced mainly in association with a Δ° (1232) and a N° (1520). The statistical significance of each peak is greater than 6 standard deviations. Masses and natural widths of these resonances are respectively M = 2020 ± 3 MeV, Λ1 = 24 ± 12 MeV and M2 = 2204 ± 5 MeV, Λ2 = 16?16+20 MeV. Our data are consistent with a small production of the narrow ~ 1935 MeV resonance already reported. Production cross sections for these new resonances are given. 相似文献
9.
L. E. Antonuk D. Bovet E. Bovet J. -P. Egger J. -F. Germond F. Goetz P. Gretillat C. Lunke E. Schwarz 《Nuclear Physics A》1984,420(3):435-460
Angular distributions of π+ and π? at 100 MeV incident energy were measured for elastic and inelastic scattering from 12C and 13C. Elastic data were obtained between 6° and 180°. Inelastic scattering on the 2+ (4.4 MeV), 0+ (7.6 MeV), 3? (9.6 MeV) and 1+ (12.7 MeV) states of 12C and on the and 11.7 MeV states of 13C was mea 12C results are compared to a Δ-hole model. 相似文献
10.
T. Fujii T. Kondo F. Takasaki S. Yamada S. Homma K. Huke S. Kato H. Okuno I. Endo H. Fujii 《Nuclear Physics B》1977,120(3):395-422
The differential cross sections for γp→π+n from hydrogen and the ratios from deuterium were measured at nine c.m. angles between 30° and 150° for laboratory photon energies between 260 and 800 MeV. A magnetic spectrometer with three layers of scintillation hodoscope was used to detect charged π mesons. The cross section for γn→π?p was obtained as a product of and the ratio. The overall features in the cross sections of the two reactions, γp→π+n and γn→π?p, and in the ratios, , agree with predictions by Moorhouse, Oberlack and Rosenfeld, and Metcalf and Walker. An investigation of the possible existence of an isotensor current was made and a negative result was found. In detailed balance comparison with the new results on the inverse reaction π?p→γn, no apparent violation of time-reversal invariance was observed. 相似文献
11.
P. Estabrooks R.K. Carnegie A.D. Martin W.M. Dunwoodie T.A. Lasinski D.W.G.S. Leith 《Nuclear Physics B》1978,133(3):490-524
An elastic Kπ partial-wave analysis is presented. It is based on high statistics data for the reactions obtained in a spectrometer experiment performed at SLAC. For each reaction, a t-dependent parametrization of the production amplitudes provides information on both the Kπ mass dependence of the production mechanisms and on Kπ scattering. Knowledge of the t-dependence then allows a calculation of the Kπ partial-wave amplitudes for Kπ masses from 0.7 to 1.9 GeV. The results of such analyses using data for (i) the neutral recoil reactions, (ii) the Δ++ recoil reactions, and (iii) both neutron and Δ++ recoil reactions simultaneously, are presented. Besides the leading JP = 1?, 2+, and 3? resonances at MKπ = 0.896, 1.434, and 1.78 GeV, there is evidence in two of the four possible partial-wave solutions for a broad P-wave resonant-like structure in the region of 1700 MeV. The S-wave magnitude rises slowly and smoothly to a maximum near 1400 MeV, but then decreases rapidly between 1400 and 1600 MeV. This structure is strongly indicative of an S-wave resonance near 1450 MeV. The charge-two Kπ reaction is dominated by S-wave scattering with a total cross section decreasing from 4 mb at 0.9 GeV to 2 mb at 1.5 GeV. Both the S-wave below 1400 MeV and the S-wave are well described by an effective range parametrization. 相似文献
12.
The three-body final states and produced from πp interactions at 1.69 GeV/c are examined. The quasi-two-body state Λ(1405)K0 is discussed in detail. In particular, the spin of Λ(1405) is determined, via the method of Byers and Fenster, to be consistent with . The Σ±π? mass spectrum is compared to that produced by various zero-range and effective-range parametrizations and the Λ(1405) is found to have a mass of 1405 MeV and width of 45–55 MeV. Production and decay characteristics of the quasi-two-body states are reported. 相似文献
13.
G. Andersson M. Asghar A. Emsallem E. Hagberg B. Jonson 《Physics letters. [Part B]》1976,61(3):234-236
Using a target prepared by on-line isotope separation, thermal neutron capture in 84Rb (Iπ = 2?) has been shown to induce proton emission to the ground state (0+) and first excited state (2+) of 84Kr. The branching ratio was measured as , favouring a assignment of the capturing state without excluding , and the (nth, p) cross section as 12 ± 2 b. The energy available for the process was determined to be 3.45 ± 0.01 MeV, in agreement with other mass data in the region. 相似文献
14.
J.R. Williams C.R. Gould R.O. Nelson D.R. Tilley D.G. Rickel N.R. Roberson 《Nuclear Physics A》1975,253(2):365-379
Electromagnetic decay properties for seventeen states in 61Ni have been examined by means of the 58Fe(α,nγ)61Ni reaction with Eα = 8 MeV and the 60Ni(d, pγ)61Ni reaction at Ed = 6 MeV. Mean lifetimes were obtained with the Doppler-shift attenuation method. Spins, parities, and mixing ratios were determined from angular correlation studies and linear polarization measurements. The combined results permit new Jπ assignments of for the levels at 1016, 1611, 2020 and 2123 keV, respectively. Experimental results, including transition strengths, are compared to shell model predictions. 相似文献
15.
H. Taureg G. Zech F. Dydak F.L. Navarria P. Steffen J. Steinberger H. Wahl E.G.H. Williams C. Geweniger K. Kleinknecht 《Physics letters. [Part B]》1976,65(1):92-96
The branching ratio has been determined to be (2.68±0.15)×10?3 for photon energies greater than 50 MeV in the KS0 rest frame. The decay KS0→π+π?γ is found to be dominated by the internal bremsstrahlung transition. The branching rato of a possible direct transition is found to be less than 0.06 × 10?3 at 90% confidence level for . 相似文献
16.
D. Bollini P. Giusti T. Massam L. Monari F. Palmonari G. Valenti A. Zichichi 《Physics letters. [Part B]》1976,61(1):96-98
The analysis of the reaction e+e?→π+π? measured at the e+e? colliding beam machine ADONE shows that, if ?′ and ?″ exist, the cross sections compare as follows (taking the ? as the reference point): : σ(e+e? → ?′ → π+π?): σ(e+e? → ?″ → π+π?) = 1: (7 ± 4) × 10?3: (1 ± 5) × 10?4. The square of the product of their couplings to the photon (γ?) and the γγ system (g?ππ) are derived. 相似文献
17.
A. Quenzer M. Ribes F. Rumpf J.L. Bertrand J.C. Bizot R.L. Chase A. Cordier B. Delcourt P. Eschstruth F. Fulda G. Grosdidier J. Jeanjean M. Jeanjean R.J. Madaras J.L. Masnou J. Perez-Y-Jorba 《Physics letters. [Part B]》1978,76(4):512-516
The pion form factor is measured in the reaction e+e? → π+π? for center of mass energies in the range 480–1100 MeV. Our results are first analysed in terms of the conventional Vector Meson Dominance formalism, and then taking into account the ωπ inelastic channel. The result of this later formalism is a pion form factor (Fπ) which fits quite well all the existing data on Fπ both in the timelike and spacelike regions, and pion mean square radius of 〈rπ2〉 = 0.460 ± 0.011 fm2 or . 相似文献
18.
C.P. Bust J.R. Carter W.W. Neale J.G. Rushbrooke D.R. Ward R.E. Ansorge B.Y. Oh M. Pratap G. Sionakides G.A. Smith J. Whitmore R. Raja L. Voyvodic 《Nuclear Physics B》1978,140(3):409-422
We have investigated the reactions . The final state is dominated by diffractive production of a system which shows a strong tendency to form . The process is also observed in this reaction, indicating an energy dependence of s?1.5±0.1. The channel shows less single diffraction, and has a doubly diffractive component consistent with pomeron factorization. Strong Δ++(Δ++) production is agoain seen, but in contrast to the channel we also observe considerable ?0 production. 相似文献
19.
The mass distributions obtained from a K?p experiment at 5.5 GeV/c are used to study the recent suggestion of an s-wave Kπ resonance at 1360 MeV. Using a model including s- and p- wave and , s-, p- and d-wave amplitudes, we analyze the spherical harmonic moments 〈Yl0〉 of the Kπ decay angular distribution in the K1 (1420) mass region and obtain the result that the reported mass of 1360 MeV does not necessarily represent the resonance position and is influenced by cuts made in the Kπ decay angle. 相似文献
20.
H.H. Bingham C.W. Farwell W.B. Fretter G.M. Irwin S. Kahn A. Lu B. Daugeras D. Fournier J. Hennessy M. Novak J.J. Veillet A.M. Cnops F.R. Huson R.I. Louttit D.J. Miller J.S. ONeall M. Di Carato M. Rollier J. Ginestet 《Nuclear Physics B》1973,52(1):31-69
Coherent production of final states from A ~ 20 nuclei by K? beams of 5.5, 10.0 and 12.7 GeV is analyzed. Final states with ? 2πO are included. Coherent production occurs (although forbidden via 0+ exchange) and is dominated by the 1 (890). The shape of the t distribution, the alignment of the produced meson and the ratio of the cross section on nuclei to that on hydrogen are consistent with optical model predictions assuming that 1 (890) are produced on single nucleons by exchange of isoscalar trajectories of natural parity (JP = 1?, 2+, etc.) and that the 1 (890) absorption in nuclear matter equals that of the K?. Coherent production (allowed via 0+, 1?, 2+, etc. exchange) is dominated by the Q phenomenon. A Dalitz plot and angular correlation analysis yields values for fractions, and shows that dominates the coherently produced Q. The helicity of the Q is found to be compatible with 0. The Q? -nucleaon total cross section is estimated to be 0.98?0.37+024 times the ? -nucleon total cross section from a comparison of the coherent Q-production cross section with corresponding hydrogen cross sections at 10 and 12.7 GeV. We observe coherent production of ω. The ration coherently produced in the Q mass region is (4 ± 1)%. Coherent production of is observed in the L region. Coherent production is not observed in the K4π channels. 相似文献