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Laser Compton Polarized e + Source for ILC. Tsunehiko OMORI (KEK). Compton meeting@LAL 24/Apr/2006. ILC : International Linear Collider. DR. e - lineac. e + lineac. DRs. ~ 50 km. E cm = 500 - 1000 GeV. start experiment at ~2015. Polarized Beams play important role - PowerPoint PPT Presentation
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Laser Compton Polarized ee++ Source for ILC
Compton meeting@LAL 24/Apr/2006
Tsunehiko OMORI (KEK)
ILC: International Linear Collidere+ lineace- lineac DRsDR
Ecm = 500 - 1000 GeV
Polarized Beams play important role Suppress back ground Increase rate of interaction (if both beam pol) Solve Week mixing of final state
start experiment at ~2015
~ 50 km
Two ways to get pol. e+
(1) Helical Undurator
(2) Laser Compton
e- beam E >150 GeV
Undulator L > 150 m
Two ways to get pol. e+
(1) Helical Undurator
(2) Laser Compton
e- beam E >150 GeV
Undulator L > 150 m
Our Proposal
Why Laser Compton ?
ii) Independence Undulator-base e+ : use e- main linac Problem on design, construction, commissioning, maintenance, Laser-base e+ : independent Easier construction, operation, commissioning, maintenance iii) Low energy operation
Undulator-base e+ : need deccelation Laser-base e+ : no problem
i) Positron Polarization.
ILC Undulator-base e+ Source
150 GeV 250 GeV 250 GeV
Experiments
Today’s talk
2. Concept of Laser Based Polarized e+ Source for ILC
Simulation study & Plan of Experimental R/D(Cavity-Compton)
1.Proof-of-Principle demonstration at KEK-ATF (ATF-Compton collab.)
Experiment at KEK, just finished
1. Experiment at KEK-ATF
120 m
ATF-Compton collaboration: Waseda, TMU, NRIS, AIST, and KEKATF: Accelerator Test Facility for ILC built at KEK
i) proof-of-principle demonstration
ii) accumulate technical imformation: polarimetry, beam diagnosis, …
ATF Experiment@KEK
No Optical Cavity at Collision Point
Compton Chamber
-rayMeasured Asymmetry
A= -0.93± 0.15 % A= 1.18± 0.15 %laser pol. = - 79 % laser pol. = + 79 %
M. Fukuda et al., PRL 91(2003)164801
Ne+ = 3 x 104/bunch Asym (expected) = 0.95%Pol(expected) = 77%
polarized e+
Measure e+ polarization : use Bremsstrahlung -ray
Pb conveter
-ray
E = 40 MeV
calculation
e+ polarization (e+ run )e- spin in Iron
e- spin in Iron
e- spin in Iron
e+ beam spin
e+ beam spin
e+ beam spinnon
A(R)= +0.60 ± 0.25%
A(L)= -1.18 ± 0.27%
A(0)= -0.02 ± 0.25%
T. Omori et al., PRL 96 (2006) 114801
A = 0.90 ± 0.18 %
Pol. = 73 %
e+ run T. Omori et al., PRL 96 (2006) 114801
Summary of Experiment1) The experiment was successful. High intensity short pulse polarized e+ beam was firstly produced. Pol. ~ 73 ± 15(sta) ± 19(sys) %
3) We established polarimetry of short pulse & high intensity -rays, positrons, and electrons.
2) We confirmed propagation of the polarization from laser photons -> -rays -> and pair created e+s & e-s.
T. Omori et al., PRL 96 (2006) 114801
Collaborating Institutes:BINP, CERN, DESY, Hiroshima, IHEP, IPN, KEK, Kyoto,
LAL, NIRS, NSC-KIPT, SHI, and Waseda
SakaeArakiYasuoHigashiYousukeHondaMasaoKurikiToshiyukiOkugi TsunehikoOmoriTakashiTaniguchiNobuhiroTerunuma,
JunjiUrakawaXArtruMChevallier, VStrakhovenko, EugeneBulyakPeterGladkikhKlausMeonig, RobertChehabAlessandroVariolaFabianZomerFrankZimmermann, KazuyukiSakaueTachishigeHiroseMasakazuWashioN
oboruSasaoHirokazuYokoyamaMasafumiFukudaKoichiroHiranoMikioTakanoTohruTakahashiHirokiSatoAkiraTsunemiand JieGao
2. Concept of Compton polarized e+ source
for ILC
Summer 2004ITRP(International Technology Recommendation Panel)
technology choice : cold LC (ILC) cold LC : super conduction RF cavity for accel.
Conceptual Design for warm LCT. Omori et al., NIM A500 (2003) 232-252
Ne+=1.2x1010/bunch
Before Summer 2004
Study Compton applied to a cold LC.
New and Improved design
Full use of slow repetition rate (5Hz)
After Summer 2004
ILC requirements
ILC requirements2x1010 e+/bunch (hard)2800 bunches/train (hard)5 Hz (we have time to store e + s)
Strategy
New: Design for cold LC (ILC) make positrons in 100 m sec. Electron storage ring, laser pulse stacking cavity : Re-use !!! positron stacking ring.
Old: Design for warm LC make positrons at once. both electron & laser beams: throw away
Basic Idea: K. Moenig P. Rainer
T. Omori et al., NIM A500 (2003) 232-252
Laser Pulse Stacking Cavity
Input laser (YAGlaser) Energy 0.7 mJ/bunch 3.077 nsec bunch spacing train length = 50 sec
Cavity Enhancement Factor =1000
Laser pulse in cavity 700 mJ/bunch single bunch in a cavity
Fabry-perot Resonator
Schematic View of Whole System
ILC: International Linear Collidere+ lineace- lineac DRsDR
~ 50 km
Schematic View of Whole System
Schematic View of Whole System
This part is necessary for ILC, This part is necessary for ILC, no matter what eno matter what e++ production production scheme is chosen.scheme is chosen.
We also haveExperimental R/D Plan
for Comptom Pol. e+ Source
Plan: Exprmntl R/D at KEK
.Put it in ATF ringOct. 2006
Hiroshima-Waseda-LAL-Kyoto-CERN-KEK Collaboration
Make a fist prototype single cavityLcav = 420 mm
.Put it in ATF ringOct. 2006
Make a fist prototype single cavityLcav = 420 mm
detail Sato's talk
Laser based scheme is good candidate of ILC polarized e+ source.
Summary of ILC source design
We have new Ideamake positrons in 100 m sec. Electron storage ring laser pulse stacking cavities positron stacking ring (= e+ DRs)
2x1010 e+/bunch x 2800 bunches @ 5Hzwith polarization ( ~ 60%)
Some values are extrapolation from old design.We need detailed simulation.
We plan to put prototype laser cavity in ATF.
Slides to answer questions
Polarization Measurement
non (Liner)
)Calculate A
)Calculate A
)Calculate A
e+ beam pol.(laser pol)
e- spin in iron (magnet pol.)
A(0) : A(0) = 0
A(R) : A(R) ~ + 0.95 %
A(L) : A(L) ~ - 0.95 %
R
L
0
expected value
(MC)
W- target
Separationmagnet
e+
e+
e-
W- target
e+Separation
magnet
polarized
e-
e-
e+ run e- run
We did e- run, also.
e- polarization (e- run)e- spin in Iron
e- spin in Iron
e- spin in Iron
e- beam spin
e- beam spin
e- beam spinnon
A(L)= -0.97 ± 0.27%
A(0)= -0.23 ± 0.27%
A(R)= +0.78 ± 0.27%
A = 0.89 ± 0.19 %
e- run
A = 0.90 ± 0.18 %
T. Omori et al., arXiv:hep-ex/0508026 KEK Preprint 2005-56
e+ run
A = 0.89 ± 0.19 %
e- run
Asymmetry Measurements
Compton Ring (e- storage Ring)
0 10 20 30 40 50 Turns
0 20 40 60 80 100 Turns
CO2 ring YAG ring
N/
elec
tron
/turn
(in
all
ener
gy o
f -
ray)
2.0
1.6
1.2
0.8
0.4
1.6
1.2
0.8
0.4
Average N/turn (in 23-29 MeV) CO2 : 1.78x1010 /turn YAG : 1.36x1010 /turn (average in 50 turns) (average in 100 turns)
e+ stacking in Damping Ring (simulation)1st bnch on 1st trn
5th bnch on 5th trn
100 bnchs on 18820th trn
10th bnch on 10th trn
before 11th bnch on 941st trn
11th bnch on 942nd trn
15th bnch on 946th trn
20th bnch on 951st trn
before 21st bnch on1882nd trn
100th bnch on 8479th trn
100 bnchs on 9410th trn
~110 sec
~10 msec
~10 msec + 110 sec ~20 msec ~100 msec + 110 sec
~110 msec
~200 msec
T=0
-0.4 0.4Longitudinal Pos. (m)
-0.0
3
0.
03E
nerg
y/En
ergy
i-th bunch on j-th DR turn
Time
e+ in a bucket
stacking loss = 18% in total