[en] An absorption band probably due to solid ammonia on interstellar grains has been detected in the infrared spectrum at 2.97 μm of the Becklin-Neugebauer object and probably in NGC 2264-IR. An ammonia-water amorphous ice mixture can explain the structure of the new band and of the 3.07 μm interstellar absorption. Laboratory data suggest that a long wavelength wing extending to 3.5 μm in interstellar dust spectra may be absorption by NH₃ x H₂O complexes in the ices. In the molecular cloud obscuring the BN object, about 20 times as much NH₃ is frozen in grains as exists in the gas phase, suggesting that gas-grain interactions may be important in the ammonia chemistry of molecular clouds. Arguments are given that interstellar features at 6.0 and 6.8 μm are also ammonia-related absorptions

[en] Spectra in the 2.5--3.3 μm wavelength region of VI Cyg 12, AFGL 2205, and AFGL 2885 were obtained in a search for bound water, hydroxyl groups, and hydrated minerals in interstellar dust. No new absorption bands were found. Comparison of expected strengths of bands of serpentine and chlorite-like minerals with the data suggests that less than 25% and 50%, respectively, of the silicate in the grains is composed of these materials

[en] Spectra in the 2.5-3.3 micron wavelength region of VI Cyg 12, AFGL 2205, and AFGL 2885 were obtained in a search for bound water, hydroxyl groups, and hydrated minerals in interstellar dust. No new absorption bands were found. Comparison of expected strengths of bands of serpentine and chlorite-like minerals with the data suggests that less than 25 percent and 50 percent, respectively, of the silicate in the grains is composed of these materials. 22 references

[en] Since the observation by the EPOS group at GS in 1985 of correlated electron-positron pair emission in superheavy ion-atom collision systems there have been many attempts to explain the phenomenon. The EPOS coincidence data show a series of narrow sum-energy lines in the laboratory kinetic energy range 610--820 keV. Recently, similar observations were reported by another group. For lack of conventional explanations for the narrow sum peaks, the production of a previously unobserved neutral system in the heavy ion collision which subsequently decays to e⁺e^- was considered as a possibility. If such an object were to exist, then it should be possible to produce it through the s-channel of ordinary electron-positron scattering. We describe the results of a set of experiments to search for such a neutral object directly in e⁺e^- collisions

[en] The search for s-channel production of light neutral particles coupled to e⁺e- has been extended by more than 3 orders of magnitude in lifetime beyond the region which is accessible to elastic e⁺e- scattering. The whole mass range 1500 approx-lt M_X⁰ approx-lt 1860 keV/c² suggested by the observation of anomalous e⁺e- pairs in heavy-ion collisions has been investigated. These measurements find no evidence for e⁺e- states within lifetime ranges (90% C.L.) of 1.4x10^-12 approx-lt τ approx-lt 4x10^-10 sec (J=0) and 1.4x10^-12 approx-lt τ approx-lt 6x10^-10 sec (J=1), assuming that the state does not break up by interacting within the target

[en] The authors describe the results of a test run involving a Transition Radiation Detector that can both distinguish electrons from pions with momenta greater than 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most efficient below 2 GeV/c while particle ID utilizing Transition Radiation is effective above 1.5 GeV/c. Combined, the electron-pion separation is better than 5 x 10². The single-wire, track-position resolution for the TRD is ∼ μm

[en] We describe the results of a test run involving a Transition Radiation Detector that can both distinguish electrons from pions with momenta greater than 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most efficient below 2 GeV/c while particle ID utilizing Transition Radiation is effective above 1.5 GeV/c. Combined, the electron-pion separation is better than 5 x l0². The single-wire, track-position resolution for the TRD is ∼230μm

[en] The authors present experimental results on rapidities, kaon and pion p_t-spectra, and two-pion correlation functions obtained for central 14.6 A GeV Si+Al and Si+Pb collisions. (HSI)

No abstract available

[en] The E877 experiment was dedicated to the study of hadron distributions in Au+Au collisions at the AGS. Here, we will mainly present results from the analysis of the data obtained from the last data taking run, which took place in the fall of 1995 and recorded 46 millions Au+Au events at 11.5 AGeV/c. The improved experimental apparatus and large statistics allowed to extend our previous measurements of particle flow [1-4] to K⁺, K^-, pbar and Λ. We will also report our latest results on two-particle correlations of like and unlike particles, as well as the measurements of double differential multiplicities of Λ-hyperons