summary of parallel session i-atauchi/talks/acfa-lc03/summary.ffir.pdf · f igu r e 4. 72: b e am...

T. Tauchi, ACFA-LC03, Mumbai, India, 18 December, 2003

Summary of Parallel Session I-A

- Accelerator related -

!Parallel Session I-A, 16 December, 2003Accelerator related: Detector Accelerator Interface

09:00 - 09:20!! T. Tauchi, KEK, Japan: !!!!!!!!!!!!!!!!!!!!!!!!!!! Interaction region and beam delivery system!09:20 - 09:40!! D. Miller, University College London, U.K.: !!!!!!!!!!!!!!!!!!!!!!!!!! Measuring the Luminosity spectrum !09:40 - 10:00! T. Sanuki, University of Tokyo, Japan: !!!!!!!!!!!!!!!!!!!!!!!!!! Status and future prospect of the GLCTA !!!!!!!!!!!!!!!!!!!!!!!!!! (Global Linear Collider Test Accelarator) !10: 00 - 10:20 G. Blair, RHUL, U.K.: !!!!!!!!!!!!!!!!!!!!!!!!! The Laserwire System at PETRA !

Beam Delivery System (BDS) Layout

4.9. Beam Delivery Section 221

4.9 Beam Delivery Section

4.9.1 Introduction

The electron and positron beams, after exiting from the main linac, before arriving at the interactionpoint (IP), pass through a beam line section which is about 1.4 km long. This section, togetherwith the beamline downstream of the IP is called ‘beam delivery section’. The beam delivery sectionconsists of four parts: switch-yard, collimator, final focus system (FFS), and beam dump. Fig. 4.63shows a schematic layout of the beam delivery section.

CollimatorBypass

Main Linac

Final Focus SystemBeam Dump

IP1

IP2

7 mrad

30 mrad

Switchyard& diagnostics

Figure 4.63: Schematic plan of the beam delivery section.

In addition to making a tiny beam spot at the IP, the beam delivery section serves multiple purposes,as follows:

• Focus the beams at the IP.

• Switch beamlines. (The beam comes from the main linac or from the bypass line and goes tothe first or to the second IP.)

• Create a finite crossing angle at the IP (7 mrad).

• Collimate the beam for eliminating the background for physics experiments.

• Protect the machine from damages due to potential failures.

• Dump the beams after collisions safely.

JLC Project Report, Revised, March 12, 2003, 3:21 P.M.

Roadmap Report,2003


fraction of the beam energy (more than a few percent). These photons also have to go to thesame water.

Fig. 4.71 shows the magnet layout of the dump line (up to the focal point for diagnostics) togetherwith the last part of the FFS.

Fig. 4.72 shows the beam spot at the diagnostics point. Here, 6 groups of points are shown. Theyrepresent the (x, y) profile of those particles with energy deviations of ε = ∆E/E = 0% (group at thebottom), −0.2%, −0.4%, . . ., −1% (at the top). One finds that the vertical width of each group issmall enough to resolve the energy to an accuracy of 10−4 near ε = 0 and 10−3 near ε = −1%.

Distance from IP (m)0 20 40 60 80 100 120

IP QD1 QF1 FFS FF

SB1B

FFSB

1A

FFSB

1

FFSB

1

FFSB

1

Dump LineQF1

QD1

BH1

BH2

QD2

QF2

BV1

BV2

1.00.5

0-0.5-1.0

(m)

Figure 4.71: Layout of the dump line

Y (m

m)

X (mm)-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8

0

0.1

0.2

0.3

0.4

Figure 4.72: Beam spot at the diagnostics point in the dump line.

The wasted beam is transported over a few hundred meters and guided to a dump system. Theamount of energy deposit is 11.5 MW (each beam) at ECM=1TeV. This will be cooled by water in


2nd FP at 140mBeam Spotat the 2nd FP

0%-0.2%-0.4%

-0.6%-0.8%-1.0%

Dumpline : Layout (2)

Apertures ?Shields ?Background: neutrons, photons to be estimated by the BDS-SIM.Better with large crossing angle of 20 mrad ?


fraction of the beam energy (more than a few percent). These photons also have to go to thesame water.

Fig. 4.71 shows the magnet layout of the dump line (up to the focal point for diagnostics) togetherwith the last part of the FFS.

Fig. 4.72 shows the beam spot at the diagnostics point. Here, 6 groups of points are shown. Theyrepresent the (x, y) profile of those particles with energy deviations of ε = ∆E/E = 0% (group at thebottom), −0.2%, −0.4%, . . ., −1% (at the top). One finds that the vertical width of each group issmall enough to resolve the energy to an accuracy of 10−4 near ε = 0 and 10−3 near ε = −1%.

Distance from IP (m)0 20 40 60 80 100 120

IP QD1 QF1 FFS FF

SB1B

FFSB

1A

FFSB

1

FFSB

1

FFSB

1

Dump LineQF1

QD1

BH1

BH2

QD2

QF2

BV1

BV2

1.00.5

0-0.5-1.0

(m)

Figure 4.71: Layout of the dump line

Y (m

m)

X (mm)-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8

0

0.1

0.2

0.3

0.4

Figure 4.72: Beam spot at the diagnostics point in the dump line.

The wasted beam is transported over a few hundred meters and guided to a dump system. Theamount of energy deposit is 11.5 MW (each beam) at ECM=1TeV. This will be cooled by water in


2nd FP at 140mBeam Spotat the 2nd FP

0%-0.2%-0.4%

-0.6%-0.8%-1.0%

IR: Crossing Angle IssueK.Yokoya

50 vs 16 fs 1.8 vs 0.6at L*=3.5m(Δyo=0.5σy)

7 mrad vs 20 mradPhysics

Stabilization R&D: Support Tube

1

234

567

8

910

1112

13141516

17

18

192021

1

234

56789

1011121314

151617

18 1920

21

1234

5678

9101112

131415161718

192021

1234

567891011121314151617

18

192021

ﾛｸ゙Hz10 100 1E3

1

0.1

0.01

10

1Z:1Z 2Z:1Z 3Z:1Z 4Z:1Z 5Z:1Z 6Z:1Z 7Z:1Z 8Z:1Z 9Z:1Z 10Z:1Z 11Z:1Z 12Z:1Z =>

A: 77.5Hz

○ Results(Taper flange, 12-M6)

B: 90Hz

C: 258Hz

D: 522Hz

AB

CD123456789

G-sensor

Fixed

101112131415161718 1920

21

Fixed

ANSYS- FEM76, 256, 489 Hz

1/10 Model

H.Yamaoka,7/30 2003

SummaryIR studies have been “completed” for L*=2m and 4.3m; as in the “Particle Physics Experiments at JLC”, KEK Report 2001-11, Aug. 2001.

Since the BDS was updated at the "GLC Project", KEK Report 2003-7, Sept. 2003, we are in the process of re-designing the IR and reexamining the relevant issues.

Stabilization R&D has been active on the support tube, FEATHER and Nano-BPM for nanometer-collisions.

Instrumentation R&D has been conducted on the pair monitor, laser wire, ODR, X-SR monitors etc. many of which have been investigated at the KEK-ATF.

4David Miller; Mumbai 16/12/03. Measuring the Luminosity Spectrum

ACFA

current dMW

Heinemeyer et al (hep-ph/0306181)

Why dmt < 100 Mev?

LC’s precision programme!

Measuring the Luminosity Spectrum by D. Miller


ACFA

Mike Hildreth suggesting “bump” spectrometer insert, upstream, in BDS.Reverts to straight-ahead when currents turned off.Blue discs are bpms on precision movers. Follow the beam as it deflects.Picture is LEP version. LC longer(P.T.),more, smaller bends

Tradeoffs - bpm bandwidth - bpm resolution - length of insertion - bend angle

Emittance dilution

\ urgent.

Absolute and Jitter Spectrometer

Jitter within train?

Do precision RF bpms work in a beamline? Will only find out if we try.


ACFA

Spectral Shape Measurement

* Synchrotron swathes from a pair of bends (downstream only, like SLD WISRD?)

* Laserwire at dispersed focus for spectrum, maybe even upstream so could use all the time, not just pulse sampling?

Spectrometry, continued

Building a collaboration for beam testsTalking to Mike Woods(SLAC), Mike Hildreth(Notre Dame), Eric Torrence(Oregon),Stan Herzbach(Amherst), David Ward(Cambridge) about a test-beam campaignusing SLAC End Station A. Heinz-Jurgen Schreiber(Zeuthen) and collaborators have DESY based plans.

All of us striving for funds to do proper experiments.


ACFAGoalsWe need a well engineered spectrometry design before theBeam Delivery System is finalised.

It would be wise to prove we can measure mt and mh to the claimed precision before funding agencies send referees to check in 2006, ahead of final approval.

So we had better start the spectrometry testssoon to match progress on Bhabha acollinearity.

We will also need a strategy for Dp/p ~10-5 measurementsbefore anyone will fund a GigaZ upgrade.There are not enough of us; happy if Asia can join in.

03.12.16 T. Sanuki, 6th ACFA WS 8

ATF -> GLCTA

• GLC electron injector complex

+

• GLC 1/5,000 of main linac

Realistic demonstration of GLC accelerator

Status and future prospect of the GLCTA by T.Sanuki


Current system

Klystron #1Klystron #2

Acc. Structure


Current situation

Ready for operation on October 1st.


Construction/power source


Accelerating structure


Schedule (example)2003 2004 2005 2006

Construction

Test

SLED II

Modulator

PPM Klystron

RF Component

Acc. Complex

GLC demonstration

16th December 2003 G. Blair, RHUL 5

Optical Scattering StructuresOptical Scattering Structures

•• Scanning of finely focused laser beam through electron beamScanning of finely focused laser beam through electron beam•• Detection of Compton photons (or degraded electrons) as functionDetection of Compton photons (or degraded electrons) as function

of relative laser beam positionof relative laser beam position•• ChallengesChallenges

-- Produce scattering structure smaller than beam sizeProduce scattering structure smaller than beam size-- Provide fast scanning mechanismProvide fast scanning mechanism-- Achieve efficient signal detection / background suppressionAchieve efficient signal detection / background suppression

The Laserwire System at PETRA, G. Blair


Laserwire for PETRALaserwire for PETRA


First Photons 31.07.03First Photons 31.07.03

Laser on Laser off

Photodiode at IP

Q-switch

Calorimeter


Results 04.12.03 DataResults 04.12.03 Data

•• Slopy Gaussian approximation of beam shapeSlopy Gaussian approximation of beam shape !!m m =(68 =(68 ±± 3 3 ±± 20) 20) ""m at low currentm at low current

!!m m =(80 =(80 ±± 6 6 ±± 20) 20) ""m at high currentm at high current

Updating the Beam Delivery System (new final focus system with longer L* etc.), interaction region is re-designing together with background re-evaluation.

Especially, (large) crossing angle issue should be carefully investigated from both sides of experimentation and accelerator.

ConclusionsACFA-FFIR subgroup

Worldwide ( in all three regions )Many high energy physicists have played important role in R&D on the stabilization, instrumentation and accelerator, cooperating with accelerator physicists.

summary of parallel session i-atauchi/talks/acfa-lc03/summary.ffir.pdf · f igu r e 4. 72: b e am...

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