# Presentation: 328289

## TOWARDS COLLABORATION“CRYSTAL COLLIMATION EXPERIMENTAT THE TEVATRON” Nikolai MokhovFermilab

***bnl - fnal- lbnl - slac***

_**US LHC Accelerator Research Program**_

- LARP Collaboration Meeting
- SLAC
- October 17-19, 2007

## OUTLINE

-  The Goal and Laundry List
-  Interested Parties and Contributions
-  CERN and INFN Support
-  IHEP Contributions
-  LARP and FNAL Support
-  AAC Support and Recommendations
-  FY08 Plan
-  Collaboration Meeting at Fermilab Dec. 6-7

**THE GOAL**

- Confirmation of models of multi-turn dynamics with crystals by exploiting channeling and volume reflection is the primary goal of the proposed experiment. Demonstration of crystal-based collimation by utilizing unique possibilities provided at the Tevatron at the end of the experimental collider run could help with:
_**Possible upgrade path for the LHC collimation system:**_
-  	enhanced performance
- 	reduced impedance
- 	heavy-ion beam halo cleaning
_**Possible complementary collimation systems:**_
- 	Fermilab Recycler in Project X
- 	ILC Beam Delivery System
- 	Muon Collider

## LAUNDRY LIST

- Beam tests in the CERN SPS extracted beams including measurements with 400 GeV protons, 200 GeV/A ions, and 30-GeV electrons and positrons.
- Beam tests as well as** **post-irradiation tests employing the Tevatron beam abort line to study damage limits of crystals; these high-priority studies would use** **mechanical, optical tests and SPS beams.
- Design and fabrication of new crystals characterized mechanically, optically and with beams.
- Studies of novel technologies to improve efficiency (multi-strip, quasi-mosaic, etc.).
- Further development of the crystal-related theoretical models and simulation tools for refined modeling of the channeling and volume reflection effects in the crystals and particle tracking in realistic multi-component collimation systems and collider lattices; full-scale modeling of the system performance in the Tevatron and LHC realms.
- Development of beam and alignment instrumentation – including single-particle tracking - adequate to crystal-based collimation, and the test of the instrumentation at the Tevatron.
- Demonstration in the Tevatron of single and multi-crystal volume reflection, and of a two-plane crystal collimation.
- Full-scale crystal collimation experiment at the Tevatron with up to three crystals, two for betatron cleaning and one for momentum, with beam diagnostics as above.
- Possible crystal collimation experiment in the SPS ring.
- Preliminary tests of crystals at U70 at IHEP (Protvino).

## INTERESTED PARTIES (1)

- A. Drees†, S. Peggs, G. Robert-Demolaize, N. Simos, D. Trbojevic
*Brookhaven National Laboratory*
- R.W. Assmann, E. Laface, M. Macri, M. Oriunno, V. Previtali,
-  S. Redaelli, W. Scandale†
*European Organization for Nuclear Research, CERN, Switzerland*
- S. Shiraishi
*University of Chicago*
- G.E. Annala, R.A. Carrigan, A.I. Drozhdin, R.P. Fliller,
-  T.R. Johnson, N.V. Mokhov†, V.D. Shiltsev, D.A. Still
*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** *
- Yu.A. Chesnokov†, 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†, V. Samsonov
*Petersburg Nuclear Physics Institute, Gatchina, Russia*
- R. Santacesaria†
*Roma – La Sapienza and INFN, Italy** *
- T.W. Markiewicz†, R. Noble, J. Spencer
*Stanford Linear Accelerator Center*

## CONTRIBUTIONS

- CERN: Experiments at H-8 beamline, manpower, beam characterization of “TeV” crystals to guarantee success at Tevatron
- INFN: manpower, crystal preparation, etching, mechanical and optical characterization, goniometer
- IHEP: manpower, crystal preparation, etching, characterization; simulations, new crystal technologies
- PNPI, JINR: manpower, theory, simulations, beam diagnostics, DAQ, new crystal technologies
- 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 SUPPORT TO THIS PROPOSAL

- 	**Ralph Assmann:** "In view of the possible limitations for conventional collimation like implemented for the LHC start-up, CERN is presently investigating possible paths to enhancing the efficiency of the LHC cleaning systems. The use of crystals has been proposed as one possibility for improving collimation. However, a clear demonstration of improved collimation efficiency in an existing storage ring is still missing.
- 	**The CERN collimation team therefore fully supports the proposed experimental investigation at the Tevatron.** The support will include advice on important experimental observables, participation to beam tests and help for analysis of recorded data. **It is our hope and expectation that Tevatron beam tests on crystal collimation provide conclusive data and directly relevant input for decisions on a possible upgrade path for LHC collimation**."

## CERN CONTRIBUTION

- 	The experiment H8RD22 approved for 3 runs and a total of 7 weeks in 07 is the biggest part of the effort of CERN. The PhD student of Ralph Assmann is the other strong contribution. Ralph, his student Valentina Previtali and Stefano Redaelli agreed to  participate to the FNAL experiment. Walter Scandale and his colleagues are already doing amazing job. He has recently had meetings with senior management at CERN and got encouraging support.

## CERN & INFN: ROMAN POTS

## INFN CONTRIBUTION

- Ferrara is ready to take the responsibility and the charge of building the goniometer and eventually incorporating the most appropriate crystal.
- The INFN financial load is estimated 100 to 500 kEuro. Ferrara's officials are asking Walter Scandale to act as the contact-man both towards Fermilab and CERN. Their wish is to proceed in collaboration with IHEP, if possible, also to use the frame of the existing INTAS program. However this is to be clarified at a later stage once the goals will be clear. This is a good news but it requires some additional discussions and work to clarify the deliverables and the time-table.
- Walter is working to get contributions of 30/500/50 kEuro from CERN/INFN/Russia, respectively.

## 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

## Ralph Assmann Comments (04/20/07) (1) 

- “I would see the following _**critical components to prove the potential of crystal collimation**_ which was unsuccessfully tried at RHIC:
- High energy, low diffusion stored beam to have impacts with small impact parameters (micron-range). Multi-turn collimation is really an edge effect-channeling experiments that hit crystals in the middle are in a very different regime. Fulfilled at TEVATRON and RHIC.
- Crystal must have minimized amorphous layer facing the beam and small surface roughness to handle small impacts. Fulfilled at TEVATRON.
- For comparison of efficiency a traditional two-stage cleaning system is required. Fulfilled at TEVATRON and RHIC.
- Crystals must be complemented by secondary collimators at reasonable phases to catch and absorb the extracted halo. Fulfilled at TEVATRON.
- Losses with/without crystals must be measured in critical locations, including the SC magnets directly downstream of the cleaning system (LHC is expected to be limited there and not in the experimental detectors). Some improvement in monitoring is required at TEVATRON in the section after the cleaning section.

## Ralph Assmann Comments (04/20/07) (2) 

- 	So there are a number of reasons why TEVATRON could give better results than RHIC. Once the predicted improvement in cleaning efficiency is proven for the first time (what is the prediction?) then crystal-enhanced collimation would in my view move beyond its status of a conceptual idea.
- 	There would still be many technical challenges need to be addressed for an LHC implementation but it is a big difference whether we would consider crystal collimation as a technique with proven feasibility or not. TEVATRON is a good opportunity to make progress now. Collimation experiments in the SPS seem very unlikely to me (absence of good two stage cleaning) and crystal tests in the LHC could not be concluded before 2009 or 2010, likely too late to include crystals into the decisions for the LHC collimation upgrade. _**Crystal collimation is a good example where the US has experimental possibilities that we presently do not have at CERN.**_
- 	Ralph
- P.S. A thought on the impact on collimator R&D: In my opinion _**crystals will never replace collimators but complement them and enhance the overall system performance**_. This means that crystal collimation also requires powerful collimators. R&D on advanced collimators is very important in any case and cannot be compromised. In the end it might be a combination of several improvements that allow us to reach our goals (like often)...”

## 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. The FY08 budget request is $220k.
- Fermilab management is supportive  to this proposal (SH, RD and YKK)

## 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.

## Decide on a need to replace the goniometer and existing crystal.
Perform detailed simulations of collimation system performance with a single strip crystal and two-plane system in the realistic Tevatron lattice for both channeled and volume-reflected beams.
Work out a plan on beam diagnostics improvement and specify new goniometer for 2009 beam studies.
Build improved beam diagnostics system and new goniometer(s) to be installed in summer 2008 shutdown.
Consider if new strip and multistrip crystals should be installed at the time.
Perform EOS (and proton-only store) angular scans in three sessions: Dec. 2007, spring 2008 and fall 2008.
Initiate 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. Once enough beam is integrated on one crystal, it should be moved back to CERN for H8 beam line characterization.

- Perform detailed simulations of collimation system performance with a single strip crystal and two-plane system in the realistic Tevatron lattice for both channeled and volume-reflected beams.
- Work out a plan on beam diagnostics improvement and specify new goniometer for 2009 beam studies.
- Build improved beam diagnostics system and new goniometer(s) to be installed in summer 2008 shutdown.
- Consider if new strip and multistrip crystals should be installed at the time.
- Perform EOS (and proton-only store) angular scans in three sessions: Dec. 2007, spring 2008 and fall 2008.
- Initiate 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. Once enough beam is integrated on one crystal, it should be moved back to CERN for H8 beam line characterization.

**FY08 PLAN (ambitious)**

**MEETING AT FERMILAB DECEMBER 6-7 **

- We are planning a first organizing meeting at Fermilab on December 6-7, 2007, with a complete LOI draft and organizational proposals distributed before that. If interested, please contact us as soon as possible.