Minutes and Summary

Main purpose of the meeting: Discussion of the low E high Beta star test to evaluate the new 2 stage collimation strategy.

General

It is difficult to move the test to Friday due to experts having now other committments (Helmut and collimation team)

Background measurements with separated beam: Not obvious that this can be done since there were some tight restrictions already when injecting into the physics optics. May be need to go back to a non colliding bunch in one of the fills. 

Beam conditions

• Five colliding bunches
• 0.6e11-0.8e11 ppb
• emittance : not special request (but > 1µm, Beam beam > 0.01)
• Wire scans
• RF 4MV as it is standard now
• Octupoles and Chromaticity as proposed by ABP: See collimation working group meeting in the talk about impedance
  • Octupoles >= 12A
  • Chroma "well above" 0

Vdm Scan

• Preparation should be a few hours (loss maps at injection with and without separation)
• Need to make sure that there is no crossing angle
• Can TOTEM make use of this run in some form?
  • SB will be declared
  • Pots will need to be behind TCT collimators + 3 sigma + 300µm (with the expected beam-sizes this is probably a bit less thatn 4 sigma outside the 13 sigma TCT setting): Is this useful ???

11m running

This run is requested by TOTEM. However it is agreed that it is the part of the entire programme with the lowest priority (however it would give valuable data to the experime)

Sequence of tests

Always do wirescans (also in between)

The time estimates are not to be taken literally: If problems or questions arise the numbers might largely underestimate the concerned item.

1. Energy matching (SPS-LHC) and general cleanup and setup (2h)
2. Beam Based alignment (2h):
   1. Primary collimators
   2. Pot alignment (1h)
   3. Secondary alignment: collimator by collimator with a hierachy test (using blow-up) after each collimator alignment.
   4. Possibly first short look at backgrounds
3. New fill: test of the configuration established above with data taking (2h)
   1. Possibly test the scraping at the end
4. New fill: test of the same configruation but with pots moved out to 3.5 sigma (2h)
   1. First move out totem by 0.5sigma, and observe rates in ALFA
   2. Move out ALFA by 0.5 sigma
   3. Possibly move out Totem completely at the end
5. New fill: test of above config but without TCTs in 1/5 (2h)
6. Optional New fill: test with crystal collimation scheme (provided that ongoing simulation deliver promising results) (2h)
7. New fill: If one of the scenarios was promising for physics try to reproduce it. 

To be clarified

Machine experts need to clarify how to efficiently reproduce the settings of the collimators in a new fill. (Beam process with hardware group was being discussed)

Why does ALFA need a VdM scan and cannot apply the same method as TOTEM to determine the luminosity (i.e. measure the coulomb and interference region)