# Presentation: 807937

## CRYSTAL COLLIMATION EXPERIMENTAT THE TEVATRON:MOU AND PLANS FOR 2008-2009

- Crystal Collimation Workshop
-  Fermilab, Batavia, IL
- December 6-7, 2007

***Fermilab***

_**Crystal Collimation**_

- Nikolai Mokhov
-  Fermilab

## OUTLINE

-  Introduction
-  Mission Statement
-  Outcome of First Studies at Tevatron
-  Collaboration and MOU
-  Staged Approach
-  Phase-I and Phase-II Deliverables & Study Plans
-  Interested Parties and Membership
-  Contributions
-  Support

## INTRODUCTION

- 	The promise of bent crystal channeling technique for beam halo collimation at high-energy colliders was recognized at the SSC in 1991. A bent crystal, serving as a primary element, coherently bends halo particles onto a secondary collimator. First successful measurements were performed at IHEP in 1998 for 1 to 70 GeV protons. Crystal collimation was studied at RHIC in 2003. Experiments by IHEP, CERN, BNL and FNAL have shown that crystals are heat- and radiation-resistant. Deflection efficiency deteriorates at about 6%/1020 p/cm2 rate.
- 	Based on results of modeling (1999, 2003), it was proposed to implement a bent crystal into the Tevatron collimation system. First measurements (2005-2006) were quite encouraging.
- 	**We propose to form a collaboration to conduct a dedicated “Crystal Collimation Experiment at the Tevatron” in the time frame required by the LHC plans.**

## MISSION STATEMENT

- We propose an experiment at Fermilab’s Tevatron to measure the predicted improvement in collimation efficiency that could be obtained by replacing amorphous primary collimators with bent crystals.
- Considering the unique possibility provided by the Tevatron Collider, and having already established fruitful collaborative efforts on crystal characterization, tests and use for collimation, we propose to test and confirm models of multi-turn dynamics with crystals by exploiting channeling and newly understood phenomena such as volume reflection as well as to further study collimation.

## MISSION STATEMENT (cont’d)

- In our view, this is a necessary first step to being able to evaluate an engineering implementation of this technique in LHC that - if proven - promises an enhanced performance of the LHC collimation system with a reduced impedance and easier implementation for heavy-ion beam halo cleaning.
- There is also an interest in crystal channeling from the ILC and Muon Collider communities.

## DELIVERABLES

- Realistic simulations of multi-turn dynamics with crystals by exploiting channeling and volume reflection, benchmarked in measurements at the Tevatron.
- Conclusive data and directly relevant input for decisions on a possible upgrade path for LHC collimation: improved collimation efficiency, reduced impedance and irradiation of downstream components in a quantitative agreement with corresponding calculations, and quantitative answers to the questions on damage limits and sensitivity analyses.
- 3.	Crystal technology, process, hardware (goniometer etc.) & instrumentation most suitable for 2-plane collimation of LHC beams, transferred to CERN.

## E0 CRYSTAL LAYOUT

## OUTCOME OF 2005-2006 MEASUREMENTS

_**When using the crystal:**_** **
**A factor of 2 was achieved in better reduction of CDF losses a half a ring or three kilometers downstream (in agreement with modeling).**
**The secondary collimator could remain further (1 mm or so) from the beam thus reducing impedance. **
**Nuclear interaction rate in the crystal was 2 to 3 times lower compared to the amorphous target, reducing proportionally irradiation of the downstream components.**_ _

## COLLABORATION AND MOU

- 	We received a very encouraging support from the LARP, Fermilab, CERN and INFN management, and also from the August Accelerator Advisory Committee at Fermilab. It was proposed that we prepare a Memorandum of Understanding (MOU), “Crystal Collimation Experiment at the Tevatron” and form an official collaboration.
- 	A draft of MOU can be downloaded from this Workshop website. 15 Institutions expressed an interest to join with proposed substantial contributions in some cases.
**MEMORANDUM OF UNDERSTANDING**
**FOR THE 2008-2009 TEST BEAM PROGRAM**

## STAGED APPROACH

- Beam studies will be performed in a two-stage way. In Phase-I, measurements will continue with the strip crystal and goniometer currently installed in the Tevatron to understand the origin of an unacceptably high “white” noise, develop a procedure for better identification of the channeling and volume reflection, and test proposed enhanced beam diagnostics.
- In parallel, more realistic and sophisticated modeling of the crystal collimation setup in the Tevatron realm will continue to better understand multi-turn dynamics in this experiment, perform sensitivity analysis by varying crystal and overall collimation system parameters, and identify places, parameters and regime of the system for the Phase-II.

## STAGED APPROACH (Cont’d)

- A team of FNAL, CERN, IHEP and JINR experts will be formed to create a simulation network and perform these realistic simulations in a coherent and consistent way. A plan will be prepared for replacement the crystal and modification of the goniometer at the first occasion, hopefully before the summer 2008 shutdown.
- At the same time, the work will be initiated on the Phase-II setup and hardware, including more optimal characterized crystals, hopefully for two-plane collimation, substantially more efficient goniometers, hopefully of push-pull type to allow alternation of two crystals without a vacuum breakout, further enhanced beam diagnostics, and corresponding control software.

## PHASE-I (2008): DELIVERABLES

- Observation of channeled and reflected beams
- Deeper investigation of multi-turn dynamics in presence of 	a crystal
- Understanding of the noise production in presence of a 	crystal
- Steady confirmation of the beam loss reduction in the CDF 	in accordance with simulation predictions for various 	scenarios
- Designs and plans for implementation and measurements of 	an enhanced collimation system for Phase-II

## PHASE-I (calendar 2008): PLAN

- Perform feasibility study of additional beam diagnostics to measure channeled, volume reflected and scattered beam profiles and rates downstream of the crystal at the collimator and instrumentation locations: (1) flying/crawling wires; (2) imaging techniques; (3) Roman Pots; (4) additional PIN diodes and beam loss monitors.
- Perform detailed simulations of the crystal collimation system – in the configuration agreed upon at the December 2007 meeting - for the current Tevatron lattice.
- Based on results of these calculations, findings with the crystal setup during investigations over the Tevatron shutdown and studies by mechanical and beam diagnostics groups, work out a plan on replacement the crystal with the previous (or new) one, modification of the existing goniometer and implementation of the improved beam diagnostics.
- Perform modifications of the existing goniometer.
- Replace the crystal.

## PHASE-I (calendar 2008): PLAN (cont’d)

- Prepare devices for a fast and precise check of the crystal alignment in situ.
- Improve existing and implement additional software as needed.
- Implement additional beam diagnostics in a staged way.
- Perform EOS beam tests as the above modifications are complete.
- Initiate design and start production work on the enhanced hardware for the Phase-II: crystals, goniometers and beam diagnostics.
- Investigate a possibility for tests to provide information about the possible deformation of the crystal or crystal holder during a vacuum baking process (up to 200 degrees).
- Investigate a possibility for a crystal damage experiment where crystals and instrumentation for assessing dose rates could be placed in the Fermilab beams.

## PHASE-II (late 2008 through 2009): DELIVERABLES

- Further investigation of multi-turn dynamics with the enhanced crystal-based collimation
- Deeper study of channeling and volume reflection for the collimation purpose
- Confirmation of the beam loss reduction in the collider detectors as predicted in simulations for the enhanced  crystal-based collimation system

## PHASE-II (late 2008 through 2009): PLAN

- Perform further data taking and data analysis: beam measurements in horizontal and vertical planes using the extended diagnostics and software.
- Perform further-refined realistic simulations.
- Evaluate needs for implementation of further enhanced beam diagnostics: OTR, luminescence screens, Roman Pots.
- If justified, implement enhanced diagnostics.
- If justified, build and implement a new goniometer.
- If justified, add a second (vertical) crystal.
- Update the control software
- Perform new data taking and data analysis.

## TEVATRON BEAM TIME REQUEST

-  Phase-I: 12 End-of-Store studies (24 hours)
-  Phase-II: 6 shifts (48 hours) – including 	non-shutdown 	installation

## INTERESTED PARTIES (1)

- A. Drees†, S. Peggs, G. Robert-Demolaize, N. Simos, D. Trbojevic
*Brookhaven National Laboratory*
- R.W. Assmann, E. Laface, M. Macri, V. Previtali,
-  S. Redaelli, W. Scandale†
*European Organization for Nuclear Research, CERN, Switzerland*
- S. Shiraishi
*University of Chicago*
- G.E. Annala, A. Apyan, R.A. Carrigan, M. Convery, A.I. Drozhdin,
- R.P. Fliller, T.R. Johnson, J. Misek, N.V. Mokhov†,
- V. Scarpine, V.D. Shiltsev, D.A. Still, D. Tinsley, J. Zagel
*Fermi National Accelerator Laboratory*
- P. Dalpiaz, M. Fiorini, V. Guidi†, A. Mazzolari
*University of Ferrara and INFN, Italy*
- M. Bozzo†
*Genova University and INFN, Italy** *
- S.A. Strokov, T. Takahashi†
*Hiroshima University, Japan*

## INTERESTED PARTIES (2)

- M. Prest†
*Insubria University and INFN, Italy** *
- A.G. Afonin, Yu.A. Chesnokov†, V.I. Kotov, V.A. Maisheev, I.A. Yazynin
*Institute for High Energy Physics, Protvino, Russia*
- Kovalenko, A. Taratin†
*Joint Institute for Nuclear Research, Dubna, Russia*
- S. Sawada†
*High Energy Accelerator Research Organization (KEK), Japan*
- A. Ratti†
*LBNL*
- Yu.M. Ivanov†
*Petersburg Nuclear Physics Institute, Gatchina, Russia*
- R. Santacesaria†
*Roma – La Sapienza and INFN, Italy** *
- T.W. Markiewicz†, R. Noble, M. Oriunno, J. Spencer
*Stanford Linear Accelerator Center*

## CONDITIONS FOR MEMBERSHIP

- To become a member of this collaboration and take part to the experiment a person should comply with at least two of the following actions:
- Perform simulations
- Participate to the experiment planning
- Participate to the installation
- Participate to the runs (take shifts)
- Participate to design and production of crystal
- Participate to design and production of goniometer
- Participate to design and production of beam diagnostics
- Participate to design and development of control software
- Perform data analysis

## CONTRIBUTIONS

- CERN: manpower, simulations, beam characterization of crystals, data analysis, LHC beam loss monitors
- INFN: manpower, crystal preparation, etching, mechanical and optical characterization, lead goniometer design and manufacturing
- IHEP: manpower, simulations, advanced crystals
- PNPI: manpower, beam diagnostics, DAQ, new crystal technologies
- JINR: manpower, theory, simulations, beam diagnostics
- KEK: manpower, beam diagnostics
- Fermilab: manpower, crystal and other hardware implementation in the Tevatron, EOS beam time, beam diagnostics, DAQ, simulations, deformation/damage tests
- BNL: manpower, beam diagnostics, deformation and damage tests
- SLAC: manpower, beam diagnostics, experiment at NLCTA with 60-MeV electrons (axial channeling)

## CERN & INFN: ROMAN POTS

## IHEP: MULTI-LAYER VR & MULTI-STRIP DEVICE

- Protvino-Ferrara

- 1.	Detailed simulations of multi-VR crystal systems for collimation in the Tevatron and LHC.
- 2.	Manufacturing new multi-layer VR crystals, their tests at IHEP  and testing at the Tevatron.
- 3.	Push-pull goniometers.
- 4.	CsI scintillator on the collimator.

_**IHEP offers:**_

## IHEP GONIOMETER DESIGN

## AAC SUPPORT

- 	August 2007’s Accelerator Advisory Committee at Fermilab fully supported this unique opportunity to perform dedicated end-of-store beam studies in the Tevatron in order to (1) confirm the Accelerator Science of this phenomenon, and (2) build a case for an LHC implementation. It called it “an experiment with great potential which could definitively establish the multi-turn physical model, building on the recent single-pass success in the H8 beam line at the SPS; it could revolutionize collimation systems in the LHC and other future accelerators”.

## AAC RECOMMENDATIONS

- 	It stated that LARP is an appropriate vehicle through which such a “high-risk, high-gain” activity could be coordinated. FY08 & 09 planning should become a high priority for LARP Accelerator Systems management. The AAC recommended:
- To enhance beam diagnostics, perhaps even including single-particle tracking capabilities.
-  Invite particle physicists to join the experiment, the approach proven to be very effective, e.g., in the SPS H-8 experiment.
-  Beam time planning for 2009 should depend on reasonable demonstrations of success in 2008.

## LARP & FNAL SUPPORT

- This proposal was presented to the LARP Collaboration meeting in April 2007 and was very welcomed at the meeting. It was noted that the timing is  right and critical (next year start would be too late). The proposal was supported by the LARP Accelerator System management, DOE Review and approved by the LARP Executive Committee.
- A refined version and a budget request were presented, discussed and supported at the LARP Collaboration meeting at SLAC in October 2007.
- Fermilab management is supportive  to this proposal.