1

FJPPL optical cavity Compton collaboration

Optical Stacking Cavity for ILC Compton e+ source

FJPPL2008@KEK15/May/2008

Junji Urakawa (KEK)

2

Today's Talk1. Introduction

2. Goal of the R&D

3. R/D status in Japan

4. Future R&D

5. World-wide collaboration6. Summary

3

Two ways to get pol. e+

(1) Helical Undurator

(2) Laser Compton

e- beam E >150 GeV

Undulator L > 200 m

Our Proposal

4

325 MHz

325 MHz

Laser Pulse Stacking Cavity

Cavity Enhancement Factor = 1000 - 105

Laser-electronsmall crossing angle

Laser bunches

Lcav = n Lcav = m Llaser

n, m : integer

Reuse high powerlaser pulse by opticalcavity.

5

Goal of our R&D a) 1.7x1012 photons x 2700 bunches/train /20% bandwidth during 100msec b) The efficiency of whole system highly depends on the optical cavity design. laser spot size is less than 10m. collision angle is less than 8 degree. enhancement factor is more than 100000. c) 220mJ @1064nm in the cavity, 5 cavities d) 2.2J @325MHz ---1kW laser oscillator e) Fiber AmplifiersAssuming 2nC/bunch, 1psec bunch length of electron bunch and 1psec laser pulse width, 325MHz collision frequency.

6

R/D Status in JapanModerate Enhancement ~ 1000

Moderate spot size ~ 30 micronSimple cavity stucture with two mirrorsGet experinence with 43MeV and 1.3GeV e- beam

Laser Undulator Compact X-ray (LUCX) Project at KEK-ATF43MeV Multi-bunch beam+ Super-Cavity = 33keV X-ray.Expected X-ray is generated.

7

Laser Undulator Compact X-ray (LUCX) Project at KEK-ATF (Kyoto-Waseda-KEK)

Multi-bunch photo-cathode RF Gun

S-band Acc. Structure

StorageLaser power36kW, 7psec(FWHM), next step :1MW

Beam size at CP 60m in

Multi-bunch e- beam 300nC at gun

43MeV Multi-bunch beam+ Super-Cavity = 33keV X-ray.

X-rayDetector

At present, laser waist size is 30m in We should reduce both beam size at CP down to 30m.33keV X-ray generation based on inverse Compton scattering is started from May 2007 with Super-Cavity.

8

e- be

am

laser beam

pulse stacking cavity in vacuum chamber

-ray Generation with Laser Pulse Stacking Cavity (Hiroshima-Waseda-IHEP-KEK)

1.Achieve high enhancement & small spot size2.Establish feedback technology3.Achieve small crossing angle4.Get experinence with e- beam

We should detect 20 ’s/collision.

9

Compact X-ray source is required from various fields. >Medical Diagnosis Angiography, Mammography … >Biological Sciences Soft X-ray microscopy … >Drag Manufacturing X-ray protein crystal structure analysis …

ApplicationApplication 1. ~Compact X-ray Sources~1. ~Compact X-ray Sources~

Our aim ~Medical Application~Development of compacthigh brightness X-ray generatorfor K-edge digital subtraction angiography.

Angiography is a procedurethat enables blood vesselsto be visualized usingthe absorption by Iodine at 33keV 1

10

100

20 25 30 35 40 45 50

Iodine K-edge

Lin

ear

Ab

sorp

tio

n C

oef

fici

en

t [u

m-1

]X-ray Energy [keV]

Iodine K-Edge E=33.169keV

2. High brightness -ray beamNondestructive assay of radio-nuclides in nuclear waste by nuclear resonance fluorescence : 1010 photons/sec ・ keV for Interrogation of fissile material in cargoes and versatile method of nondestructive analysis of both radioactive and stable nuclides.

10

Future R/D

1. Points for high enhancement factor

2. Points for small spot

remove/suppress vibrationestablish feed-back technology

2 - Lcav --> +0good matching between laser and cavity

Achieve both high enhancement(1000) & small spot (30m) (less stabile) &

(less stabile)

(Mirror R = 99.7%-R=99.9%-R=99.99%-R=99.999%?)Next step : from 1000 to 10000 or 100000

Next step : from 30m to 10m or 6m

11

3. Points of R/D (continued)

Number of -rays strongly depends oncrossing angle

Achieve smaller crossing angle

10W, 357MHz

02000400060008000

0 10 20 30crossing angle

Counts/crossing

--> Small crossing angle is preferable.--> constraint in chamber design

ATF

e- bunch length = 9 mm (rms)

Ne = 1x1010/bunch

(In the case of 1mm bunch length, this dependence is not strong.)Short bunch beam is preferable.

Next step : from 12 degree to 8 degree or 5 degree.

12

Mirror R (mm)

rms laser spot size (micron)

250 88

211 35

210.5 30

210.1 20

210.01 11

210.001 6

L

R

Laser stacking cavity with

Two Spherical MirrorsChoice of R and spot size

our choice for 1st prototype

L = 420.00 mm

concentric configurationR + R ~ L

13

World-Wide-Web of Laser Compton

Laser Compton

ILC e+

CLIC e+

Optical Cavity

High powerlaser

e- sourceILC, ERL

Medicalapplications

Industrialapplications

ERL 4th Generationlight source

LWmonitor

collider Polari-metry

X-raysource

Nuclear Assay Diagnostic

14

Summary

2. Laser stacking cavity is a key.3. In Japan, we are generating X-ray and -ray by installing the stacking cavity in LUCX and ATF-DR.4. In France, we are developing a very advanced cavity with 4 mirrors. In 2009, a 4 mirror cavity will be installed in ATF-DR for -ray generation.-next talk.

1. Compton e+ source is an advanced

alternative of ILC e+ source

5. We have world-wide collaboration for Compton. Not only for ILC e+ source. Also for many other applications.

15

Extra Slides

16

Expected Number of -rays at ATFNumber of -rays/bunch

Electron :Ne = 2x1010 (single bunch operation)Laser : 10 W (28 nJ/bunch)Optical Cavity: Enhancement = 1000

Ng =2500/bunch X-ing angle = 5 degN=1300/bunch X-ing angle = 10 degN= 900/bunch X-ing angle = 15 deg

Number of -rays/second

Electron :Ne =2x1010 (multi-bunch and multi-train operation)Electron 20 bunches/train, 3 trains/ringLaser : 10 W (28 nJ/bunch)Optical Cavity: Enhancement = 1000

Ng = 3.4x1011/sec X-ing angle = 5 degN = 1.7x1011/sec X-ing angle = 10 degN = 1.1x1011/sec X-ing angle = 15 deg

17

18

What we want

ILC YAG case

(Snowmass 2005)

Now on Going

at KEK-ATF

Achieved in 2004 (Takezawa(Kyoto U) et al) at KEK-ATF

Electron Energy (GeV) 1.3 1.3 1.3

Ne/bunch 6.2E10 2.0E10 1.0E10

Electron repetition rate (MHz) 325 357 357

Hor. Beam size (rms,us) 25 79 79

Ver. Beam size (rms,us) 5 6 6

Bunch length (rms,mm) 5 9 9

Laser type (wavelength) YAG(1064nm) YAG(1064nm) YAG(1064nm)

Laser frequency (MHz) 325 357 714

Laser radius (rms, um) 5 29 125

Laser pulse width (rms,mm) 0.9 0.9 0.9

Laser pulse power /cavity 750J x 1000 28nJ(10W) x 1000 1nJ(0.3W) x 65

Number of laser cavities 30 1 1

Crossing angle (degree) 8 12 90

by H. Sato (Posipol 2006)Cavity History in Japan

19

Compton for "2 x 6 km DR": no simulation yet

20

Collaborating Institutes:BINP, CERN, DESY, Hiroshima, IHEP, IPN, KEK, Kyoto,

LAL, NIRS, NSC-KIPT, SHI, Waseda, BNL, and ANL Sakae Araki, Yasuo Higashi, Yousuke Honda, Masao Kuriki, Toshiyuki Okugi, Tsunehiko Omori, Takashi Taniguchi, Nobuhiro Terunuma, Junji Urakawa, X. Artru, M. Chevallier, V. Strakhovenko,

Eugene Bulyak, Peter Gladkikh, Klaus Meonig, Robert Chehab, Alessandro Variola, Fabian Zomer, Alessandro Vivoli, Richard Cizeron, Frank Zimmermann, Kazuyuki Sakaue, Tachishige Hirose, Masakazu Washio, Noboru Sasao, Hirokazu Yokoyama, Masafumi Fukuda, Koichiro Hirano,

Mikio Takano, Tohru Takahashi, Hirotaka Shimizu, Shuhei Miyoshi, Akira Tsunemi, Li XaioPing, Pei Guoxi, Jie Gao, V. Yakinenko, Igo Pogorelsky, Wai Gai, and Wanming Liu

PosiPol CollaborationWorld-wide Collaboration

POSIPOL 2007LAL-Orsay, France23-25 May

POSIPOL 2006 CERN April 2006

http://posipol2006.web.cern.ch/Posipol2006/ http://events.lal.in2p3.fr/conferences/Posipol07/