# Presentation: 406696

## GAN Scenario for the US LHC Accelerator 
Research Program 

W.C. Turner
Center for Beam Physics
LBNL

Presented at the
GAN Tools Workshop
LBNL
26 Aug 2002

_**US LHC ACCELERATOR RESEARCH PROGRAM (US LARP)**__**                               **_

- GAN Scenario for the US LHC Accelerator
- Research Program
- W.C. Turner
*Center for Beam Physics*
- LBNL
- Presented at the
- GAN Tools Workshop
- LBNL
- 26 Aug 2002

## Brief history

**BNL, FNAL and LBNL are collaborating on the US LHC Accelerator Project**
- Started in 1997
- Provides accelerator hardware to CERN – IR quadrupoles, beam separation dipoles, IR absorbers etc
- Ends in 2005 with delivery of equipment to CERN, prior to LHC commissioning and operation which begins in 2007
**A new collaboration began in 2002 – the US LHC Accelerator Research Program (US LARP) with the purpose of**
- Allowing the US to assist CERN with commissioning and operation of equipment supplied by the US
- Providing an avenue for US accelerator specialists to participate in the frontier energy machine and develop their skills
- Training the next generation of accelerator specialists
- Helping position the US to be the site of a possible future hadron collider

## Components of US LARP

**Commissioning**
**Accelerator physics**
**Beam instrumentation**
**New IR quads (NbSn****3****)**
- All three labs have activities in each of the four components.

## GAN and LHC

**For many reasons it seems unlikely that the full blown GAN will be implemented for the LHC Accelerator (ATLAS and CMS detectors possibly a different story)**
- Construction of LHC is well along, GAN not included or actively being worked on at CERN
- Pre existing chain of injection accelerators dating back to 1950s
- No motion within European member countries to host LHC GAN control rooms
- Limited scope and resources of US LARP
**However two areas where GAN tools could be usefully employed on LHC are**
- Accelerator physics (participation in Machine Development studies)
- Instrumentation (remote data logging and operation)

## Culture

- Sociological issues are perceived as a main roadblock to employment of GAN
- Using GAN tools for MD studies and logging and operation of a limited set of beam instruments supplied by the US could help gain acceptance in the community for the full blown GAN
- MD studies carried out jointly between participating institutions would help foster a team culture
- Significant on site presence of participants is necessary to develop a team culture
- Envision participants spending six months to a year on site during initial commissioning and frequent periodic visits afterward
- The host and remote institutions must perceive a mutual benefit to using GAN tools
- In the long run the use of GAN tools allows the possibility of broader and more frequent participation with less expense – how this works out in practice would be a critical litmus test of the concept

## Controls

**Beam control and operation functions are imagined to be carried out by an on site team not by a remote team(s)**
- Alleviates most of the critical security concerns
- Avoids one of the major sociological hurdles
**Controls of some beam instrumentation parameters not effecting beam operation is desirable**
- Eg. Running test and debug operations to analyze problems or verify equipment is working
- Useful if the expert(s) are at a remote site

## Machine development (MD) studies

**Dedicated runs undertaken to improve machine performance, ie luminosity (event rate)**
- In LEP ~1wk/mo was dedicated to MD studies, in LHC ?
**Examples**
- Improvement of algorithms for bringing beams into collision
- Improvement of injection efficiency
- Investigation of tune space
- etc
**Envision running simulation codes and comparing with experimental results**
- Electron cloud
- Beam-beam
- ???
**Need flexibility in recording the suite of instrumentation needed for particular MD study**

## Two examples of instrumentation functions

**Luminosity monitor**
- Bring beams into collision
- Maintain beams at optimum luminosity
- Log the luminosity, the luminosity lifetime and the beam-beam separation of the ~2835 colliding bunch pairs (40MHz)
- Monitor crossing angle
**Longitudinal density**
- Monitor abort gap density
- Measure longitudinal bunch profiles; core, tail
- Monitor ghost bunch density
- Measure untrapped beam fraction prior to ramp
- Injection timing, longitudinal multi bunch instabilities
**Envision using the GAN tools for **
- Remotely logging and analyzing data during routine beam operation
- Exploiting these instruments for MD studies
- Running test procedures to verify operation

## What tools are needed

- Remote replication of the control room environment
- Duplication of on site Video monitor displays of machine operation
- Video monitors dedicated to viewing the participants on both ends
- High quality audio
- Meeting room for development and discussion of run plans, analysis, information exchange at shift changes etc
- Electronic logbooks
- White boards
- Computers for logging data streams, analyzing and displaying summary data, running simulations

## Summary

- The US LARP offers the possibility for a limited utilization of GAN tools for Machine Development studies and beam instrumentation functions that could simultaneously
- Help gain acceptance for a more pervasive use of these tools in future accelerators – eg NLC
- Increase the participation and cost effectiveness of US physicists in LHC operations
- Benefit CERN
- The opinions expressed in this presentation are those of the author and not necessarily of everyone in the US LARP collaboration