New Evidence for Supernarrow Dibaryons Production in pd Interactions

The analysis of new experimental data, obtained at the Proton Linear Accelerator of INR, with the aim to search for supernarrow dibaryons in the $pd\to ppX_1$ and $pd\to pdX_2$ reactions is presented. Narrow peaks with an experimental width of 5 MeV at masses of 1904$\pm 2$, 1926$\pm 2$, and 1942$\pm 2$ MeV have been observed in missing mass $M_{pX_1}$ spectra. In the missing mass $M_{X_1}$ spectra, the peaks at $M_{X_1}=966\pm 2$, 986$\pm 2$, and 1003$\pm 2$ MeV have been found. The analysis of the data obtained leads to the conclusion that the observed peaks in $M_{pX_1}$ spectra are most likely supernarrow dibaryons, the decay of which into two nucleons is forbidden by the Pauli exclusion principle. An alternative interpretation of the spectra by assuming a decay of the supernarrow dibaryons in "exotic baryon states" with masses $M_{X_1}$ is discussed.Comment: 17 pages, 6 figures. Considerably expanded version accepted for publication in Eur. Phys. J. A; a discussion, 4 figures and several references have been added, the title has been change

Fishing for Narrow Dibaryons in pd->pX Reaction

An analysis of experimental data, obtained at the Linear Accelerator of INR, is carried out with the aim of searching for supernarrow dibaryons in the reactions pd->p+X and pd->p+pX_1. Dibaryons with masses 1904\pm 2, 1926\pm 2, and 1942\pm 2 MeV have been observed in M_{X} missing mass spectra. In M_{X_1} missing mass spectra, the peaks have been found at M_{X_1}=966\pm 2, 986\pm 2, and 1003\pm 2 MeV. These values of M_{X_1} coincide with the ones obtained by a simulation of a decay of the dibaryons into \gamma+pn. The analysis of the data obtained leads to the conclusion that the observed dibaryons are supernarrow dibaryons, the decay of which into two nucleons is forbidden by the Pauli exclusion principle. A possible interpretation of exited nucleon states with small masses is suggested.Comment: 4 pages, 2 figures, aipproc.sty (included); Proceedings of the VII Conference "Intersections Between Particle and Nuclear Physics", Quebec, Canada, May 23-27, 200

Extraction of neutron-neutron scattering length from nn coincidence-geometry nd breakup data

We report preliminary results of a kinematically complete experiment on measurement of nd breakup reaction yield at neutron beam RADEX of Institute for Nuclear Research (Moscow, Russia). In the experiment two secondary neutrons are detected in geometry of neutron-neutron final-state interaction. Data are obtained at energy of incident neutrons En = 40 - 60 MeV for various divergence angles of two neutrons ΔΘ = 4, 6, 8º. 1S0 neutron-neutron scattering length ann were determined by comparison of the experimental dependence of reaction yield on the relative energy of two secondary neutrons with results of simulation depending on ann. For En = 40 MeV and ΔΘ = 6º (the highest statistics in the experiment) the value ann = -17.9 ± 1.0 fm is obtained. The further improving of accuracy of the experiment and more rigorous theoretical analysis will allow one to remove the existing difference in ann values obtained in different experiments

Study of d + d → 2He + 2n reaction at deutron energy of 15 MeV

Section II. Experimental Investigations of Nuclear Reactions Mechanism