1. Lecture 2 - Overview of Accelerators II
ACCELERATOR PHYSICS
MT 2011
E. J. N. Wilson

2. Lecture 2 – Overview II- Contents
Weak focusing in a synchrotron Strong focusing
The “n-value”
Cosmotron people
Strong focusing
CERN at BNL
CERN 25 GeV PS
CERN’s rings
SPS
Center of mass v. Fixed target
The first collider -AdA
ISR AND PS
Luminosity
Physics of electrons v protons
LEP
Superconducting magnets

3. Weak focusing in a synchrotron
The Cosmotron magnet
Vertical focussing comes from the curvature of the field lines when the field falls off with radius ( positive n-value)
Horizontal focussing from the curvature of the path
The negative field gradient defocuses horizontally and must not be so strong as to cancel the path curvature effect

4. The “n-value”
As the C magnet saturates the n value – which is the rate of droop – increases

5. Cosmotron people E.Courant -Lattice Designer Stan Livingston - Boss
Snyder -theorist
Christofilos - inventor
FOURGUYS.pct

6. Strong focussing

7. CERN at BNL Odd Dahl, Frank Goward, and Rolf Widerö (right hand trio)
Fig.3(CERNVISITORS).pct

8. CERN 25 GeV PS

9. CERNS RINGS

10. SPS

11. Center of mass v. Fixed target

12. AdA - The first collider e-plus-minus

13. ISR AND PS
ISR+PS.pct

14. Luminosity
Imagine a blue particle colliding with a beam of cross section area - A
Probability of collision is
For N particles in both beams
Suppose they meet f times per second at the revolution frequency
Event rate
Make big
Make small
LUMINOSITY

15. SPS

16. Physics of the electron v. protons
When we collide Protons we collide complex assemblies of three quarks
Only two quarks interact
Their available energy is on average only 10% of the total centre of mass energy
We do not know which quarks they are
Hence in some ways 100 GeV LEP is as good as 1000 GeV TEVATRON
HENCE THE RETURN TO LEP AFTER SPS
AND THEN LHC AFTER LEP

17. LEP
LEP(small).pct

18. Inside LEP

19. The Tevatron at FNAL
Fermilab’s superconducting Tevatron can just be seen below the red and blue room temperature magnets of the 400 GeV main ring.

20. The Large Hadron Collider (LHC)
The project was first proposed in 1982 at a Snowmass Study, organised by the APS. At a cost of $2.9B to $3.2B, it was supposed to re-establish US supremacy in the field of high-energy particle physics following the discovery in Europe of the W and Z.
The next step was carried out. By 1986 a detailed design study, by a Central Design Group set up under Maury Tigner at Lawrence Berkeley Laboratory, was complete and in 1987 President Reagan set in motion the search for a site. In 1988 Waxahatchie, Texas was announced as the successful candidate and construction commenced. This decision was, perhaps, influenced by then Vice-President George Bush (senior) of Texas, Jim Wright of Fort Worth, then Speaker of the House of Representatives, and a powerful Senator, Lloyd Bentsen, also from Texas.
Meanwhile the cost, taking into account the more realistic estimates of the Central Design Group, and including the proposed experimental facilities, had risen from the initial estimate of 2.9 B$ to 3.2 B$ and then to 5.3 B$ in 1986.
The DOE took over the management of the project from the CDG and determined that the traditions of technical and cost control that had been built up in large laboratories, like Fermilab, were to be abandoned in favour of methods judged more appropriate for a project of this size. Contracts were placed and subsystems procured in a manner that had hitherto been used for large defense projects. This led to further escalation, first to 5.9 B$ and then, as review teams included into account “site-specific” costs, to 7.2 B$ and then 8.2 B$ (DOE, 1991). The final straw came when an Independent Cost Estimating Team of the DOE (1993) added 2.5 B$ for “peripheral expenses which would not have been incurred if the SSC had not been there”. The SSC was given a year’s reprieve but by 1994 when the US Congress saw fit to cut their losses and terminate the project the estimate was 11.8 B$.
The reasons for cancellation were not entirely budgetary. There was a rival project – the Space Station – that many in the House of Representatives preferred.

21. Superconducting magnets

22. Summary Strong focusing CERN at BNL CERN 25 GeV PS
Center of mass v. Fixed target
The first collider -AdA
ISR AND PS
Luminosity
SPS
Antiproton production and cooling
CERN Antiproton Accumulator
LEP
Superconducting magnets