Anomalous strong interaction in pionic Mg

Absolute pionic x-ray intensities have been measured for Mg and Fe. The accuracy achieved was 2% of the line intensity for the most prominent transitions. In the Balmer series of Mg and the Paschen series of Fe the crossover transitions were found to be even more attenuated than the transitions between circular states, as deduced, for example, by comparison with muonic atoms; no crossover transitions were observed in the Fe Balmer series. According to cascade calculations based on the experimental intensities more than half of the pions are absorbed in Fe already from levels with principal quantum number n > 17 by strong interaction.

Section: Iil Experimental Resultscontrasting

confidence: 77%

Absolute pionic x-ray intensities in Mg and Fe

Hartmann

Daniel

Neumann

et al. 1991

“…The X-ray tran- The single spectrum together with prompt and delayed coincidence spectra are shown for comparison. After background subtraction the peak intensities were determined in the regions indicated by arrows sition intensities have been determined by fitting a step function as described in [16] to the background of the energy spectra. The ratios of the intensities are shown in Table 1.…”

Section: Data Reductionmentioning

confidence: 99%

The probability of prompt and delayed fission of muonic237Np

Schrieder

David

Hänscheid

et al. 1991

Self Cite

Fission fragments from the reaction 237Np(p ,y f) have been measured in coincidence with muonic X-rays. The efficiency of the fission fragment detector is determined from (p , 7f)-data of the same experiment. The total fission probability per p-stop Pt has been measured as well as the fission probabilities Pf of the non-radiative muonic (3d~ ls)-and (2p~ls)-transitions; the latter has been divided into two parts leading to different mean excitation energies E: Pt=(54_+17)%, Pf(3d--*ls)=(41__21)%, Pf(2p--~ls, E= 6.218 MeV) = (61 _+ 19)%, andPf(2p~ls, E = 6.525 MeV) = (57 _+ 18)%. The influence of the muon on the fission barrier is discussed. The fission probability after muon capture is compared with a calculated value using a distribution of nuclear excitation energies following muon capture and the fission probability as measured in a a38U (3He, ~f)-reaction.

“…Thus, it has been tried to fit this spectrum with the program FIT [9] over a wide energy range taking all mnonic X-ray lines and the background as described in ref. [10] carefully into account. A gaussian function has been used for the description of the observed structure.…”

mentioning

confidence: 98%

Experimental evidence for muonicX-rays from fission fragments

Rösel

Karpeshin

David

et al. 1993

Self Cite

Abstract:In the spectrum of muonic X-rays of 238U measured in coincidence with prompt fission events a structure has been found which is attributed to 2p--*ls transitions of the muon attached to heavy fragments. The intensity Is of this structure relative to the strength Ipi observed for prompt fission has been determined to be I,/Iv. f = (6.0-{-2.1) %. Although the experimental significance for the appeareance of this phenomenon is weak, this is the first experimental indication for its occurence. 36.10.Dr Non-radiatlve (n.r.) transitions in heavy muonlc atoms excite the nucleus which then may decay via prompt fission. Contrary to delayed fission occuring as a result of p-capture by the nucleus, the muon survives the prompt fission process and is attached predominantly to the heavy fission fragment [1] forming an atom with the muon in the ls state. In several theoretical investigations it has been stated that the muon canpopulate also excited states [2][3][4][5][6][7]. The p-populates an excited level of a fission fragment either due to internal conversion of the excitation energy of the fragment to the p- [2,3] or as a consequence of the muon transitions during the fission fragment formation. In the first case the probability depends on the energy and multipole composition of the electromagnetic transition of the fragment. In the latter the population strength turns out to be influenced by the dynamics of the fission process. Theoretical predictions for the population probability of the 2p level of the heavy fragment muonic atom range between 1% [6] up to 10% per prompt fission [3,4]. No X-rays from such levels have been reported so far. PACS:Recently, the results of a 23SU(p-, 7f) experiment devoted to the study of prompt fission have been published [8]. The experimental set-up consisted of two Germanium diodes with BGO-Compton suppression for the X-ray detection and a multi parallel plate avalanche counter filled with metallic ~3SU foils, which served as an active target. The muonlc X-rays from the 23sU target have been recorded in coincidence with fragments of prompt as well as delayed fission. The muonic X-ray spectrum coincident with prompt fission should also Present address: * Heuft-Systemtechnik GmbH, W-5475 Burgbrohl, Germany ~'* Klinik und Poliklinik ffir Nuklearmedizin der Universiffit Wfirzburg, W-8700 Wfirzburg, Germany *** Bayer AG, W-5090 Leverkusen, Germany + Gesetlschaft ffr ProzeBsteuerungs-und Informationssysteme mbH, W-8750 Aschaffenburg, Germany contain the muonic X-rays from fission fragments. The energies of both lines of the 2p--,ls transition complex of the most probable isotope 140v s4 Me are lying at 3.7 and 3.8 MeV, respectively. Due to the charge distribution the 2p--,ls transitions of the muonie heavy fragments should occur within an energy interval of about 700 keV [3]. An additional complexity results from the mass distribution. Furthermore, Doppler broadening smears out the separate lines [4]. Fig. 1 shows the spectrum recorded in coincidence with prompt fission by one of th...