[en] This project involved continued participation by the Physics Department at the Mayaguez Campus of the University of Puerto Rico (UPR) in high energy physics experiments carried out at Fermilab. The UPR is a member of the E831 collaboration which includes Fermilab and leading US, Italian, Brazilian and Korean universities. E831 is an upgrade to the E687 spectrometer with the goal of a tenfold increase in the statistics for the study of the photoproduction and decay of charmed particles. This spectrometer has been significantly upgraded to maintain and expand its capabilities even at considerably higher beam intensities. E687 completed its last data run in January 1992. Approximately 100,000 charm events were fully reconstructed from this data and results of the analysis have appeared in several publications. The UPR has been participating in E687 since 1985 when the experiment was in its early stages of construction. A grant from the DOE Division of High Energy Physics (starting in April 1994) and another from the DOE EPSCoR Program (starting in October 1994) allowed a considerable increase in the activities of the UPR group. Given the group's capable performance, the responsibilities assigned to it by the collaboration have increased to the point where they now include four major detectors in E831. All four detectors were ready on time for the start of the E831 run in July 1996. This is a remarkable performance if one considers that there is only one senior member in the group and that the students are all MS or undergraduate students. The group has also been active in the development of simulation, data acquisition and analysis software

[en] This project involved collaboration in the design, construction and testing of a prototype chamber capable of detecting Cerenkov rings. The chamber incorporated several novel techniques in that it used parallel-plate pad readout and a Cesium-iodide (CsI) solid photocathode. The pad system used gas multiplication where the gas was kept at low pressure to minimize photon losses due to absorption and back-scattering and to minimize ion collection times. Low pressure also lowers the chamber response to charged particles. The chamber gas was ethane at 20 torr and the chamber was operated at room temperature. The chamber was built at the University of Pennsylvania by a University of Puerto Rico graduate student, Jorge Millan. Initial tests at Pennsylvania using a hydrogen-discharge lamp indicated a quantum efficiency of 13% at 190 nm. The chamber was then tested in the M-Test beam line at Fermilab and behind the C3 beamline dump at Brookhaven Lab. Cerenkov rings were clearly observed with each photoelectron typically exciting one pad. On average each ring had five struck pads and only 10% of the events had hits in the center due to the charged particle. These results indicate that a RICH detector using a solid CsI photocathode coupled to a low-pressure, parallel-plate pad chamber is an excellent device for particle identification in high-rate environments when there is a need to cover large areas with minimum expense

[en] The high energy gamma rays from the radiative capture of B¹⁰ filtered neutrons in Mn⁵⁵ and Co⁵⁹ were measured and analyzed in terms of the statistical and direct capture model of nuclear reactions. A high resolution NaI(Tl)-Ge(Li) pair spectrometer was used to detect the gamma rays. Correlations between (n,γ) and (d,p) intensities were determined for these nuclei. The distributions of the reduced intensities were also studied and compared with predictions of the statistical model. Finally an attempt was made to determine a direct capture component in the ⁶⁰Co ground state partial cross-section. It was found that the ground state data could be explained with the resonance amplitudes alone. (author)

No abstract available

[en] A transportable traveling flux detector (TFD) system for use in power reactors has been developed and tested at Chalk River Nuclear Labs. in Canada. It consists of a miniature fission chamber, a motor drive mechanism, a computerized control unit, and a data acquisition subsystem. The TFD system was initially designed for the in situ calibration of fixed self-powered detectors in operating power reactors and for flux measurements to verify reactor physics calculations. However, this system can also be used as a general diagnostic tool for the investigation of apparent detector failures and flux anomalies and to determine the movement of reactor internal components. This paper describes the first successful use of the computerized TFD system in an operating Canada deuterium uranium (CANDU) power reactor and the results obtained from the flux distribution measurements. An attempt is made to correlate minima in the flux profile with the locations of fuel channels so that future measurements can be used to determine the sag of the channels. Twenty-seven in-core flux detector assemblies in the 855-MW (electric) Unit 6 reactor of the Ontario Hydro Bruce B Generating Station were scanned

No abstract available

[en] We discuss a method for correcting the bias in the limits for small signals if those limits were found based on cuts that were chosen by minimizing a criterion such as sensitivity. This type of bias is commonly present when a 'minimization' and an 'evaluation' are done at the same time. We propose to use a variant of the statistical bootstrap to adjust the limits. A Monte Carlo study shows that these new limits have correct coverage

[en] It was forecast that from 1986 to the late 1990s the nuclear plus hydraulic baseload generation capability within Ontario Hydro will frequently exceed the total system electrical demand. As a result, nuclear units will increasingly be required to meet changes in demand in order to minimize the operating costs. This paper discusses Ontario Hydro's electrical system requirements regarding nuclear generating stations and the key issues affecting their operation. It summarizes the economic impact of nuclear maneuvering, reviews the operating experience to date, and presents the long-term strategy that is being pursued. The results of our analysis indicate significant savings on fuel replacement costs due to nuclear maneuvering capability. This is achieved by eliminating the need for shutting down baseload nuclear units and then having to replace the required demand load from maneuverable but expensive coal-fired stations. Between 1986 and 1987, Pickering NGS-B and Bruce NGS-B demonstrated the nuclear maneuvering capability of CANDU reactors and saved Ontario Hydro one million dollars in fuel costs. A typical load cycle at Bruce NGS-B consisted of reducing power to 50% FP, holding at that power, then returning to full power when system required it. Deeper nuclear maneuvers, where power is reduced to 20% to 25% FP, have also been successfully demonstrated. A joint work program within Ontario Hydro is being pursued by Operation, Research, Design, and Systems Planning departments to anticipate potential areas of concern during the coming periods of significant unutilized energy. In particular, the potential long-term effects on equipment include a scheme to anticipate, monitor and evaluate the impact on equipment reliability and performance

No abstract available

[en] Cerebro-hepato-renal syndrome is a rare disorder that is transmitted by autosomal recessive inheritance. Children with this syndrome present mongoloid facies and severe muscle hypotonic at birth. Scimitar-like knee calcifications are considered a pathognomonic feature of this disorder. We present two patients with Zellweger syndrome, according to the diagnosis suggested by our Radiodiagnostic Service. Our objective is to stress the importance of the radiological findings, which in many cases are decisive in establishing the definitive diagnosis. (Author) 10 refs