共查询到20条相似文献,搜索用时 31 毫秒
1.
J. Heintze G. Heinzelmann P. Igo-Kemenes R. Mundhenke H. Rieseberg B. Schürlein H.W. Siebert V. Soergel H. Stelzer K.-P. Streit A.H. Walenta 《Nuclear Physics B》1979,149(3):365-380
The decay K+ → e+υγ has been investigated. For the structure-dependent part with positive γ-helicity (SD+) the branching ratio is obtained from 51 ± 3 events observed in the kinematical region Ee ? 235 MeV, Eγ > 48 MeV and θeγ > 140°. For the corresponding part with negative γ-helicity we obtain an upper limit Γ(SD?)/Γ(SD+) < 11 (90% CL) from the sample of electrons with energies 220 MeV ? Ee < 230 MeV and with no γ in the backward direction. This upper limit implies that the ratio of structure-dependent axial vector amplitudes lies outside the region .For the decay the limit 90% confidence level) was found. 相似文献
2.
B. Jongejans R. Blokzijl J.C. Kluyver G.G.G. Massaro H. Voorthuis M. Cerrada Ph. Gavillet R.J. Hemingway M.J. Losty J.J. Engelen W.J. Metzger C.L.A. Pols B. Foster L. McDowell J. Wells 《Nuclear Physics B》1978,139(4):383-393
A 2.5 standard deviation signal is observed for the decay . From this signal a partial width of 13.0 ± 5.0 MeV for the decay mode is deduced under the assumption that the ππ system is in an I = 1 state. For the rare decay mode no signal is observed. The following upper limits can be given for the decay widths: , , . 相似文献
3.
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
4.
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
5.
E. Eisenhandler W.R. Gibson C. Hojvat P.I.P. Kalmus L.C.Y.Lee Chi Kwong T.W. Pritchard E.C. Usher D.T. Williams M. Harrison W.H. Range M.A.R. Kemp A.D. Rush J.N. Woulds G.T.J. Arnison A. Astbury D.P. Jones A.S.L. Parsons 《Physics letters. [Part B]》1973,47(6):531-535
We present measurements from a spark chamber experiment of the differential cross-sections for p → π?π+, K?K+ at 20 momenta in the range 0.8–2.4 GeV/c (c.m. energy 2.02 to 2.57 GeV). The c.m. angular range was . There are about 2000π?π+ events and about 300 K?K+ events at each momentum. 相似文献
6.
New experimental as well as theoretical results allow us to attribute the v2 line (25,654 cm?1at 4.2 K) of the copper chloride absorption spectra, to a direct optical transition between a Γ7 free hole and a positive X+2 charged exciton. 相似文献
7.
D.G. Burke W.F. Davidson J.A. Cizewski Ronald E. Brown J.W. Sunier 《Nuclear Physics A》1985,445(1):70-92
The reaction has been studied using 17 MeV polarized tritons from the Los Alamos National Laboratory tandem Van de Graaff accelerator. The α-spectra were analyzed with a Q3D magnetic spectrometer. The overall energy resolution was typically ~ 15 keV (FHWM) and angular distributions of cross sections and analyzing powers were obtained for levels up to ~ 2.7 MeV. The fact that spins and parities for all levels up to ? 2 MeV were previously known from an extensive series of (n, γ) studies made it possible to determine specific two-quasiproton structures for many bands from the present results. The Kπ = 2+ γ-vibrational band was found to have a large admixture, consistent with the predicted microscopic composition of this phonon, but no component was observed. The Kπ = 04+ band at 1833 keV has ~ 25% of the two-quasiproton strength. This is in excellent agreement with the Soloviev model but is inconsistent with the interacting boson model, in which the Kπ = 04+ band is composed almost completely of multiphonon configurations that should not be populated in a single-nucleon transfer reaction. The two-quasiproton and the two-quasineutron states are mixed strongly with each other, but the two Kπ = 3? bands composed of antiparallel couplings of the same particles are not. A good qualitative explanation of this mixing pattern is provided in terms of the effective neutron-proton interaction. 相似文献
8.
L. Görlich B. Niczyporuk M. Różańska K. Rybicki J. Turnau H. Becker G. Blanar W. Blum H. Dietl J. Gallivan B. Gottschalk E. Lorenz G. Lütjens G. Lutz W. Männer D. Notz R. Richter J. De Groot 《Nuclear Physics B》1980,174(1):16-44
The reaction π?p→K+K?n has been studied on a hydrogen target (27 000 events) at 18.4 GeV/c and on a polarized target (54 000 events) at 17.2 GeV/c. A combination of results of both experiments allows a partial-wave analysis of the K+K? system between 1.1 and 1.74 GeV mass without any model assumptions. In general our fits yield unique solutions. Using results of our previous analysis of π+π? final states and assuming the dominance of the positive G-parity states in the K+K? system, the branching ratios of partial waves into are determined. The S-wave appears to be mainly a broad ε (1300) with . The weak P-wave can be described by a tail of the . The D-wave is interpreted in terms of a superposition of f(1270) + A2(1310) + f′(1515) resonances. The fit yields for the f(1270) and BR(ππ/all) = 0.027?0.013+0.071 for the f′(1515). The F-wave shows the g(1690) meson with . All the above values refer to the t bin between 0.01 and 0.20 (GeV/c)2. Some results are also given for the high-t region. 相似文献
9.
Based on the proper connected diagram expansion, we calculated cyclotron resonance widths Γn associated with neighboring Landau states (n, n +1) for free electrons in interaction with more than one kind of impurities. In 3D usual Matthiessen's rule Γn=Γ(1)n+Γ(2)n+…where Γ(i)n represent widths calculated separately for each kind, is obtained. In 2D a new rule: is obtained. 相似文献
10.
V.V. Abramov A.V. Alekseev B.Yu. Baldin S.I. Bityukov V.Yu. Glebov A.S. Dyshkant V.N. Evdokimov A.N. Krinitsin V.I. Kryshkin N.Yu. Kulman G.I. Lanshchikov V.K. Myalitsyn Yu.M. Melnik A.P. Orlov V.I. Povzun R.M. Sulyaev L.K. Turchanovich Yu.N. Vrazhnov V.V. Zmushko 《Nuclear Physics B》1980,173(2):348-364
The cross sections for π±, K±, p, and production in pp collisions have been measured at transverse momenta from 0.48 up to 2.21 GeV/c at 70 GeV. The data are compared with results obtained at lower and higher proton energies and also with the quantum chromodynamics parton model (QPM) calculations. Common behaviour of the cross sections of the form in the energy range above 200 GeV does not take place at lower energies. Qualitatively QPM fits the data and the best agreement is for π+/π? and K+/π+ ratios. 相似文献
11.
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
12.
D. Denegri Y. Pons R. Barloutaud A. Borg C. Louedec M. Spiro K. Paler T.P. Shah S.N. Tovey B. Chaurand B. Drevillon G. Labrosse R. Lestienne R.A. Salmeron 《Nuclear Physics B》1975,91(1):54-68
We have studied the reaction K-p → K-π+π-π+π-p at 14.3 GeV/c to search for evidence of the double dissociation process . In the channel π1-π2-Δ++ (1236) there is evidence for simultaneous production of low-mass enhancements in the and Δ++(1236)π2- subsystems which correspond to the and decay modes. In this particular final state the double fragmentation system is produced with a cross section of the order of a few microbarns. Our data are consistent with the factorizable pomeron exchange model of double diffractive dissociation. 相似文献
13.
I.V. Ajinenko Y.A. Belokopitov P.V. Chliapnikov L.N. Gerdyukov V.V. Kniazev A.I. Kurnosenko A.K. Likhoded V.M. Perevoztchikov V.N. Riadovikov A.M. Rybin O.G. Tchikilev V.F. Tchunikhin V.A. Uvarov A.P. Vorobjev 《Nuclear Physics B》1980,176(1):51-60
The inclusive production of and Ξ? hyperons is investigated in K+ p interactions at 32 GeV/c. The production cross sections, 36.4±9 μb for the and 6.5±3 μb for the Ξ?, are rising strongly with energy similarly to and Λ production in K+ p interactions. The are produced preferentially in the forward direction in the c.m.s., while the Ξ? are produced dominantly backwards. The average transverse momenta and 〈pT〉Ξ?=0.58±0.09 GeV/c. 相似文献
14.
The polarized excitation and emission spectra of the U6+ molecular centers giving the most intense emission lines at 18 940 cm?1 and 19 285 cm?1 are presented and analyzed in detáil. From the polarization experiments, it is shown that the symmetry of the centers is C4v and that the symmetries of the observed electronic states are Γ2, Γ1 and Γ5. Finally, an electronic model is proposed which associates the emission and excitation lines of the U6+ centers in the visible region to transitions between the fundamental state and the states of the excited configuration . 相似文献
15.
A. Berglund T. Buran P.J. Carlson C.J.S. Damerell I. Endo A.R. Gillman V. Gracco R.J. Homer M.J. Hotchkiss A. Lundby M. Macri B.N. Ratcliff A. Santroni T. Tso F. Wickens J.A. Wilson 《Physics letters. [Part B]》1975,57(1):100-104
For the first time, the reactions π+p→K+∑+ and K?p→π?∑+ have been studied in the same apparatus. This has been done at an adequately high momentum (10.1 GeV/c) to allow a check of the prediction of exchange degeneracy, that the differential cross sections should be converging at high energy. We have measured the cross section for momentum transfers t between tmin and t = ?0.3 (GeV/c)2. We find that for both reactions the differential cross section shows an exponential fall, with no deviations right in to t =tmin (where some other experiments have shown a dip in the cross section). Furthermore, we find the magnitude of the differential cross sections to be closely similar at t = 0, with a ratio However, the slope for the positive reaction is about 19% steeper than that for the negative reaction. 相似文献
16.
G. Otter H. Remplewski G. Rudolph L. Becker R. Klein W. Lohmann H.J. Schreiber K. Böckmann U. Idschok J. Lowsky B. Schröder D.J. Kocher D.R.O. Morrison K.-L. Wernhard T. Coghen K.W.J. Barnham R. Eason H. Rohringer 《Nuclear Physics B》1979,155(2):295-306
Results are presented for p → (ΛK+) dissociation in the reactions K?p → ΛK+K? and and π±p → ΛK+π±at 10 and 16 GeV/c. The cross sections for the low-mass ΛK+ enhancement are compatible with the energy dependence σ ∝ plab?0.3. The t′ spectra or the (ΛK+) threshold enhancement are exponential in shape. Its decay angular distribution reveals neither s-channel nor t-channel helicity conservation. The relative probabilities of the processes dissociation are in the ratios 100 : 10 : 0.2, independent of the nature of the incident particle. 相似文献
17.
G. Dehm G. Göbel W. Wittek G. Wolf G. De-Jong S. Tavernier P. Cornet P. Dufour F. Grard V.P. Henri R. Windmolders G. Charrière W. Dunwoodie A. Grant Y. Goldschmidt-Clermont F. Muller J. Quinquard 《Nuclear Physics B》1974,75(1):47-58
The decay branching ratios of K10 (1420) into K+π?, K0π+π? and K1+(892) π? are measured in the charge exchange reaction using data from a K+d bubble chamber experiment at 4.6 GeV/c incident momentum. For the branching ratio is obtained. The results are compared with previous measurements. 相似文献
18.
In the presence of right-handed currents including , it is emphasized that the dominant parity-violating (-conserving) Hamiltonian for nonleptonic decays of charmed hadrons transforms like of SU(4), and leads to distinctive results especially in D+ → KSπ+, F+ → μ+νμ and D0 → K?e+νe, etc. 相似文献
19.
H. Braun M. Cornelssen H.-U. Martyn O. Erriquez S. Natali F. Romano D. Bertrand M. Csejthey-Barth J. Lemonne P. Renton P. Vilain D.C. Cundy T.I. Pedersen D. Waldren 《Physics letters. [Part B]》1973,47(2):185-188
The q2 variation of the factor in the decay K+→π0e+ν has been studied using a sample of even detected in the CERN 1.1 m3 heavy-liquid bubble chamber. The data are consistent with a linear development with λ+=0.027±0.008. 相似文献
20.
V.A. Ionescu Jean Kern R.F. Casten W.R. Kane I. Ahmad J. Erskine A.M. Friedman K. Katori 《Nuclear Physics A》1979,313(3):283-306
Low and high energy spectra from thermal neutron capture in 237Np have been studied over the energy ranges 25 to 650 keV and 2600 to 5500 keV. Primary transitions from neutron capture in four resonances have been observed between about 4800 and 5400 keV. Using 12 MeV deuterons, (d, p) spectra at three angles have been observed with a magnetic spectrograph. A nuclear level scheme for 238Np has been constructed by combining the results of the above measurements with previous data from a study of the 242mAm α-decay. The Nilsson model has been used to interpret the level structure. Including results from the previous α-decay study, nine rotational bands can be assigned. The Nilsson configurations (Kπ [Nn3ΛΣ]) and band-head energies are: 2+π[642↑]?ν[631↓], 0.0 keV; 3+π[642↑]+ν[631↓], 86.6 keV; 3?π[523↓]+ν[631↓], 136.0 keV; 2?π[523↓]?ν[631↓], 182.8 keV; 5+π[642↑]+ν[622↑], 278.1 keV; 0+π[642↑]?ν[622↑], 332.5 keV; 5?π[523↓]+ν[622↑], 342.6 keV; 0?π[523↓]?ν[622↑], 286.0 keV; 6?π[642↑]+ν[743↑], 301 keV. The measured (d, p) reaction cross sections are compared with theoretical calculations based on these assignments. The Gallagher-Moszkowski rule is found to be valid in the four cases where we have observed both parallel and antiparallel coupled bands with and . The lowest levels of the two K = 0 bands have spin I = 1; Newby odd-even shifts can be determined in both cases. 相似文献