Tevatron Crystal Channeling

T-980 Collaboration:FNAL, SLAC, BNL,CERN,PNPI,IHEP,INFNDean Still

April 13, 2009

All Experimenters Meeting

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Overview Explanation of crystal channeling Tevatron Crystal Setup End of Store (EOS) Measurements for

2008/2009 Moving to a Beginning of Store (BOS) Study Preliminary Results from BOS Conclusion

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Explanation of Crystal Channeling

Ray Fliller- Halo 03

Tevatron E0 Crystal Layout

crystalE03H Collimator

3.5 mmchanneled beam

23.731 m

Pin Diode

LE033 BLM

FlyingWire

23.731 m

33.115m

LE0PIN

Channeled beamAt E03H

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EOS Measurement for 2008/2009

Thus far, T980 has requested 7 EOS studies since Sept 14, 2008 provide data and understanding on how to utilize crystal collimation.

These 7 EOS can be broken down into 2 categories:1) 1- 5 EOS establish channeling with reinstalled O shape

crystal (installed AUG 2008) AND attempt to understand 2 fundamental questions about what has been demonstrated.

2) 6-7 EOS test for incorporating the crystal into the Tevatron automated halo removal system

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Summary of EOS Work

Analysis & Slide: Vladimir Shiltsev

From very EOS on Sept 14 EOS demonstrated channeling & improved loss localization with new goniometer, characterized crystals, and enhanced beam diagnostics, BUT … there are 2 basic questions to understand:

1) Why channel width and VR efficiency are different and worse than 2005.

2) Why the channeled beam does not appear to have the correct displacement at E03H collimator.

All these are important questions to answer which tell us about crystal performance, efficiencies, …

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Learned Info from EOS

Newly learned information from studies with new instrumentation included:

1) Mainly abort gap beam was being channeled.

With this knowledge coupled with the fact that there is a large miscut angle maybe could answer some of the initial questions. - Is it related to beam dynamic or crystal property.

Channeled abort gap beam

Bunched beam

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Effects Due to Crystal Mis-Cut AngleAccording to most recent simulations

Having wrong sign(+) of large miscutangle can explain broading of channel width& difference in displaced beam at collimator.

February 3, 2009 A.Drozhdin, A,Apyan

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Overview

Plan and Motivation for 2009 End of Store (EOS) Measurements for

2008/2009 Moving to a Beginning of Store (BOS) Study Preliminary Results from BOS Conclusion

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Plan and Motivation for 2009The ultimate goal of T980 for 2009 is to have enough understanding and practice

to use single plane crystal collimation as part of the normal halo removal operation for every store. 

By having the capability of incorporating crystal channeling into every store or many stores gain benefits for: More possible hours of utilizing crystal channeling over ONLY EOS. Gain practical and operational experience using crystal channeling. Hopefully demonstrate reduction of halo loss for either or both CDF and D0

detectors.

Of Course the caveat to incorporating crystal channeling for every store:it can have NO negative impact on the Tevatron Collider Run

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Moving to Beginning of Store Studies (BOS)

Things for certain to this point:•Crystal channeled beam could be collimated & intercepted locally (by E03H) thus improving collimation system efficiency•Results are reproducible contrary to earlier studies.

There are many questions about performance and efficiencies to still be answered but we felt we are very confident in the one fact that channeledbeam can be collimated.

We wanted to move to our main goal which is to use the crystal during a store to start seeing if it can truly reduce proton halo back grounds.

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T-980 Review Process Aug 7, 2008 : T-980 had a formal Installation review by Accelerator

Division, CDF and D0 to confirm readiness and impact to collider program for crystal collimation. Additional mandatory review for determining readiness for conducting a BOS.

Feb 4, 2009: T-980 held BOS review which recommended BOS

with EOS confirmation of automated placement of crystal.

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EOS for Store 6901 – Test for BOS

Auto insertion of crystal Horizontal worked well

After angle set toChanneling, completedE03H scan to verify channeling

Used EOS of 6901 to test full auto insertion of crystal and check that channelingCan be established.

Setting the crystal angle To channeling

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Overview

Plan and Motivation for 2009 End of Store (EOS) Measurements for

2008/2009 Moving to a Beginning of Store (BOS) Study Preliminary Results from BOS Conclusion

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Finding channeling point for BOS

Store 6903 BOS No clear channel point Store 6901 EOS clear channeling

Channeling should be ~-250urad

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Preliminary Look at 1st BOS - Store 6903

Crystal AngleDrift ~ 90urad

Loss in bunchAt E03H

Losses in Abort gap at E03H

This is crystal channel point.

Crystal angle drifted ~ 90urad over 16 hours during store.

This is most likely do to Thermal heating of Goniometer.

Need better angular Control.

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-400 -200 0 200

Crystal Angle (urad)

2000

7000

12000

17000

22000

27000

T:E

1L

AB

T L

oss

(h

z)

20

40

60

80

100

120

T:L

E0

PIN

Lo

ss (

hz)

Store 6903 EOS angle scanT.E1LABTT.LE0PIN

Angle Scans at the End of Store 6903

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-350 -300 -250 -200 -150

crystal angle (urad)

0

5000

10000

15000

20000

Loss

(hz)

6903_EOS_ANG_SCAN_E1LABT.PAGE1

T.E1LABT

Spread of Angles Around Channel

-285 -252

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-310 -300 -290 -280 -270 -260

Crystal Angle (urad)

0

40000

80000

120000

T:E

1lA

BT

Lo

ss (

hz)

0

50000

100000

150000

T:E

1L

BN

C lo

ss (

hz)

Store 6903 Losses around channelT:E1LABTT:E1LBNC

ChanneledDistributionAngles

Store 6903 BOS – Losses at the collimator

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Halo Losses During BOS Store 6903

Store 6906 – Normal store No crystal Store 6903 – Crystal Collimation used

CDF proton halo lossD0 proton halo lossLE033 – local crystal lossCDF Luminosity

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Crystal Angle Stabilization Software Added software to correct for temp. effects that change crystal angle.

Corrects to ~ 4urad around a given set point.

Max deviation ~ 14 urad during motor reversal periods.

Crystal Laser Angle(urad)

4 urad

Crystal AngularMotor counts

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Conclusion First big transition step in being able to use crystal collimation at

the beginning of store (BOS).

There was no negative effect to the collider store from the BOS and hopeful that crystal collimation can be used for many stores.

The angle of the crystal changed by ~90urad of the store which has been addressed as a software angle feedback system.

Crystal collimation during the BOS showed signs of channeling at E0 but it is too early to demonstrate effect around the ring or benefits to CDF and D0 IP’s.

There is still much work to be done to understand and demonstrate effects to miscut angle and effect of losses around the ring.