A general view of the Padua PEPR. On the left is the CRT system, in the centre is the modular digital controller and on the right is the computer and operator console.

(Photo INFN Padua)

groups and of the President of INFN, C. Villi, also participated. The construction of PEPR started in 1971 and has been carried out in close collaboration with the Oxford Nuclear Physics Department where a PEPR was built some years ago (see August issue 1970, page 258). It was realized by the Padua 'strong inter­ actions bubble chamber group' under M. Cresti, in collaboration with the INFN Section and the Physics Insti­ tute. The Directors of the Physics Institute, M. Baldo Ceolin and of the 20 000 events of this type have been Further information can be obtained INFN Section, C. Ceolin spoke at the measured. from H. Hahn or G. Kalbfleisch at inauguration ceremony. The use of PEPR to measure Brookhaven, A. Pevsner at Johns Many of the system's features have pictures other than those from bubble Hopkins or L. Sulak at Harvard. been designed to make PEPR capable chambers has also been studied. In of measuring film from large bubble particular, automatic measurement of chambers. The signal processor is the co-ordinates and magnitude of almost completely digital and all the stars on astronomic plates and of the parameters of the system are con­ equal level curves on geographic maps Machine performance trolled by software through a modular have been shown to be feasible. This reaches new heights digital controller whose flexible struc­ opens a new and very wide field of ture allows for future modifications application. The recent performance of the or expansions. PEPR is equipped with synchrotron at the Fermi National a hardware TV system, which has Accelerator Laboratory was reported proved a very important tool both for by P.V. Livdahl in the opening paper hardware tests and in the production BROOKHAVEN of the 1975 Con­ runs. ISABELLE ference in Washington, 12-14 March. The cost has been kept low by Summer Study The accelerator now has 70 com­ building PEPR almost entirely in the pleted experiments under its belt and laboratory and by connecting it to a The 1975 ISABELLE Summer Study another 36 are under way. They involve computer of much smaller size than will be held at Brookhaven from 14- physicists from 68 research centres in those used elsewhere in similar instal­ 25 July. Its aim is to improve, re­ the USA and 43 from other countries. lations. inforce or modify the concepts which For the month beginning 14 Feb­ The system started production on have gone into the proposal for the ruary the machine had a very success­ a bubble chamber experiment in June construction of the 200 GeV proton ful run at 380 GeV rather than its usual 1974, producing 60 000 measure­ storage rings, looking at the experi­ peak energy of 300 GeV. Operation ments of three prong events for which mental physics as well as the machine at the higher energy came on very only the interaction vertex in one view design aspects. smoothly in comparison to previous had been predigitized. Recently a new The opening two days will be used attempts and intensities of over type of measuring technique has been to review the present status of the 1013 per pulse were reliably put into operation. The beam tracks project and are open to all interested available on a 15 s cycle with a 1 s are automatically found and followed physicists. For the remainder of the flat top. by PEPR up to an interaction vertex, time, participants will get their heads Improvements in the power supply where the hardware TV system is used down on specific topics in working program made a major contribution to ask the operator to record the topo­ groups covering such things as Ex­ to the performance. The new pro­ logy of the events. In this way the perimental insertions, Performance gram, controlled by on-line com­ total cross-section is measured at a limitations, Stacking and accelera­ puter, generates new cycles for the rate of 150 to 200 events per hour. tion, -proton option.... currents much more rapidly.

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