Intersecting storage rings

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The Intersecting Storage Rings ( ISR ) were two opposing proton - storage rings with about 300 meters diameter at CERN , which were operated from 1971 to 1984.

history

In 1956, a group at the Midwestern Universities Research Association (MURA) developed proposals for how particle bunches could be collected in storage rings using beam stacking and then brought to collision. By colliding particles in opposite directions, the energy supplied can be used far better than when colliding with a static target , where a considerable part of the energy is lost due to the law of conservation of momentum in the mean kinetic energy of the fragments.

After the commissioning of the 28 GeV Proton Synchrotron (PS) at CERN in 1959, the MURA proposals were taken up and further elaborated, since in this way the effectively usable energy of the PS could be increased from 7 GeV to 56 GeV. A storage ring for CESAR electrons was built to test the MURA concept . A proposal for the construction of the ISR was submitted in 1964 and approved the following year; France provided an area of ​​about 40 hectares adjacent to the CERN site, on which construction began in January 1966. The first ring was put into operation in October 1970 for test purposes, the second ring followed in January 1971. The first collisions took place on January 27, 1971. The official inauguration and commissioning of the ISR took place in October 1971.

At the ISR, extensive experience has been gained in the operation of collision storage rings, e.g. B. The technology of stochastic cooling was developed here. This experience was used to carry out collision experiments between protons and antiprotons at the Super Proton Synchrotron (SPS) in 1979 .

Operations ceased in June 1984 and the workforce switched to the Large Electron-Positron Collider .

technology

The two rings had a diameter of 300 m each, an opening cross-section of 160 × 52 mm and were located in a 15 m wide tunnel. There were eight intersection points between the two rings at which particle packages could be brought to collide. The ISR were located about 200 m from the PS and were connected to the PS through a tunnel in each direction for filling with protons. The protons were accelerated in the PS, but the protons in the ISR could be accelerated up to 31.4 GeV.

In order to achieve sufficient luminosity , the number of particles per particle packet had to be increased considerably by means of beam stacking compared to the number of particles supplied by the PS. Up to 400 parcels delivered by the PS were collected on a 60–70 mm wide and 3–10 mm high orbit, and stored there typically for 11 hours, in one case even for 345 hours.

In particular, the high beam currents of several amperes and the long dwell time of the beam placed new demands on the magnet systems and the vacuum quality of the steel pipes. During the operating time, the evacuated beam tube was hit and perforated several times by an out of control proton beam.

Web links

Individual evidence

  1. ^ A b c K. Johnsen: CERN Intersecting Storage Rings (ISR) . In: Proc. N / A. Acad. Sci. USA . 70, No. 2, 1973, pp. 619-626. PMC 433316 (free full text).
  2. ^ Kurt Huebner: Design and construction of the ISR. (pdf) Retrieved November 10, 2018 (English).
  3. ^ A b The Intersecting Storage Rings. Retrieved September 22, 2018 .
  4. ↑ a b Kjell Johnsen, CERN: The ISR in the time of Jentschke ( English ) Cerncourier. Jun 1, 2003. Retrieved Dec 3, 2009.
  5. ↑ Intersecting Storage Rings collection, ISR ( English ) 1961-1983. Retrieved Nov. 30, 2009.

Coordinates: 46 ° 14 ′ 5 "  N , 6 ° 2 ′ 35"  E ; CH1903:  four hundred and ninety-two thousand three hundred and forty-eight  /  121324