Merging the CEM2k and LAQGSM Codes with GEMINI

An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions contained in the code CEM2k and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) are merged with the well-known sequential-binary-decay model GEMINI by Charity. We present some results on proton-induced fragmentation, fission-product yields and on particle spectra predicted by these extended versions of CEM2k and LAQGSM. We show that merging CEM2k and LAQGSM with GEMINI allows us to describe many fission and fragmentation reactions in addition to the spallation and evaporation reactions which are already described well by these codes. Nevertheless, the current version of GEMINI we use does not provide a completely satisfactory description of some complex-particle spectra, fragment emission, and spallation yields for some reactions, and is not yet a universal tool for applications. Our results show that GEMINI contains a powerful model to describe evaporation/fission/fragmentation reactions and often provides better results when compared to other models, especially for emission of heavy fragments from reactions on medium-heavy nuclei (where most other models simply fail), but it must be further extended and improved in order to properly describe arbitrary reactions.Comment: Revised version of an ND2004 contribution (2004, Santa Fe, USA): minor revision of the text, Fig. 5 revised, references updated. We thank Dr. Claude Volant for noticing that the stated values of the fission delay time used in GEMINI were in error for several reactions in the earlier version of this pape

Observation of structures at ∼17\sim 17 and ∼38\sim 38 MeV/c2^{2} in the γγ\gamma\gamma invariant mass spectra in pC, dC, and dCu collisions at plab\textit{p}_{lab} of a few GeV/c per nucleon

The results of an analysis of the invariant mass spectra of photon pairs produced in dC, pC and dCu interactions at momenta of 2.75, 5.5 and 3.83 GeV/c per nucleon respectively, are presented. Signals in the form of enhanced structures at invariant masses of about 17 and 38 MeV/c2 are observed. The results of testing of the observed signals, including the results of the Monte Carlo simulation are presented. The test results support the conclusion that the observed signals are the consequence of detection of the particles with masses of about 17 and 38 MeV/c2 decaying into a pair of photons.Comment: arXiv admin note: text overlap with arXiv:0806.279

Resonance structure in the {\gamma}{\gamma} and π0π0\pi^0\pi^0 systems in dC interactions

Along with $\pi^0$ and {\eta} mesons, a resonance structure in the invariant mass spectrum of two photons at M{\gamma}{\gamma} = 360 \pm 7 \pm 9 MeV is observed in the reaction d + C \rightarrow {\gamma} + {\gamma} + X at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are {\Gamma} = 64 \pm 18 MeV and $\sigma_{\gamma\gamma}$ = 98 \pm 24 {\mu}b, respectively. The collected statistics amount to 2339 \pm 340 events of 1.5 \cdot 10^6 triggered interactions of a total number ~ 10^12 of dC-interactions. The results on observation of the resonance in the invariant mass spectra of two $\pi^0$ mesons are presented: the data obtained in the d + C \rightarrow {\gamma} + {\gamma} reaction is confirmed by the d + C \rightarrow $\pi^0$ + $\pi^0$ reaction: $M_{\pi^0\pi^0}$ = 359.2 \pm 1.9 MeV, {\Gamma} = 48.9 \pm 4.9 MeV; the ratio of Br(R\rightarrow{\gamma}{\gamma}) / Br(R\rightarrow$\pi^0\pi^0$) = (1.8 {\div} 3.7)\cdot10^-3.Comment: 10 pages, 11 figure