[en] The steady state and transient behaviour of the nitrogen polarisation in dynamically polarised irradiated ammonia has been experimentally investigated. It is concluded from the results obtained with both ¹⁴N and ¹⁵N that these nuclei are in spin temperature equilibrium with the protons under the conditions normally existing in polarised targets and hence the nitrogen polarisation may be calculated from the measured proton polarisation. (orig.)

[en] The most ambitious implementation of the Jefferson Lab data acquisition system (CODA) to date is for the CLAS spectrometer in Experimental Hall B. CLAS has over 40,000 instrumented channels and uses up to 30 front-end (FASTBUS/VME) crates in the DAQ subsystem. During the initial experiments the authors found that performance of the fully instrumented DAQ system did not scale as expected based on single point to point benchmarks. Over the past year the authors have been able to study various performance bottlenecks in the CLAS DAQ system including front-end real time performance, switched 100BaseT Ethernet data transport, and online data distribution and recording. Performance tuning was necessary for components on both real time (VxWorks) and UNIX (Solaris) operating systems. In addition, a new efficient Event Transfer System (ET) was developed to provide faster online monitoring while having minimal impact on data throughput to storage. They discuss these issues and efforts to overcome the real world problems associated with running a high performance DAQ system on a variety of commercial hardware and software

[en] Measurements have been made on borane-ammonia at SLAC using low temperature (1 K) ''in beam'' irradiation. Up to 30% polarization was obtained after the material had been annealed. Also it has been shown that high temperature (77 K) irradiation of solid ammonia in a reactor produces a material which has excellent dynamic nuclear polarization properties, so it was considered that it would be worthwhile to investigate the borohydrides using the same technique. (orig./HSI)

[en] The Event Transfer system enables its users to produce events (data) and share them with other users by utilizing shared memory on either Solaris or Linux-based computers. Its design emphasizes speed, reliability, ease of use, and recoverability from crashes. In addition to fast local operation, the ET system allows network transfer of events. Using multi-threaded code based on POSIX threades and mutexes, a successful implementation was developed which allowed passing events over 500 kHz on a 4 cpu Sun workstation and 150 kHz on a dual cpu PC

[en] The authors discuss the design and performance of a Trigger Supervisor System for use in nuclear physics experiments at Jefferson Lab. They also discuss the enhanced features of a new Trigger Supervisor Module now under construction

[en] A test facility has been constructed to carry out fundamental measurements and the development work on polarised target materials. It is, in fact, a polarised target without the facility for beam access. It has been designed so that rapid sample changes can be made and also to have maximum flexibility in its operating and measurement conditions. The apparatus has been used for research in two main areas, firstly an investigation of the general properties and polarisability of the two borohydrides NH₃BH₃ and NH₄BH₄ when electron centres are produced by irradiation and secondly for the study of the polarisation of the nitrogen nuclei in irradiated ammonia. (orig.)

[en] A Q-meter system for the measurement of the proton polarisation in polarised targets is described, in which the real part of the output signal, rather than its magnitude, is used to obtain the polarisation. It uses a radio frequency phase sensitive detection technique. Calculations are presented which show that a very high linearity is obtained with this system when used under the experimental conditions obtained in typical polarised targets. A description of the electronic circuits used to implement such a system is given, together with measurements of their performance. (orig.)

[en] The polarization of nitrogen nuclei in both ¹⁴NH₃ and ¹⁴ND₃ have been investigated in some detail. The material ¹⁵NH₃ has also been investigated. The ¹⁵N nucleus has spin 1/2, and consequently there is no quadrupole broading and this makes its polarization much simpler to measure. (orig./HSI)

[en] The aim of the CP LEAR experiment is to study symmetry-violation effects, making use of tagged K⁰'s and anti K⁰'s. The detector, although missing some electronic components, has been operational for a few weeks at the end of 1989 at the CERN Low-Energy Antiproton Ring (LEAR). At the moment, the analysis of the data is in progress. This paper gives a description of the experimental method and of the detector; the sensitivities of some measurements and some preliminary results are also discussed. (orig.)

[en] The CPLEAR experiment is aiming at precise CP violation tests using initially pure K⁰- and anti K⁰ beams from the intense source provided by the annihilation of the LEAR vector p-beam in hydrogen. The strangeness tagging efficiency and the systematic errors have been studied and found to be in agreement with the design specifications. The measurement of the differential time asymmetry of the π⁺ π^- decays allowed the direct observation of differences in the decay rates of particles and antiparticles. The CP violating parameters were determined as vertical stroke η_±vertical stroke = (2.32 ± 0.14).10^-3 and φ_± = 42.3 ± 4.4 . First results in the reconstruction and analysis of the neutral kaon decays into two neutral pions and the K_e3 decay are presented. (orig.)