T.Takahashi Hiroshima Optical Cavity R&D for Photon Colliders T.Takahashi Hiroshima Univ. 26 May...
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Transcript of T.Takahashi Hiroshima Optical Cavity R&D for Photon Colliders T.Takahashi Hiroshima Univ. 26 May...
![Page 1: T.Takahashi Hiroshima Optical Cavity R&D for Photon Colliders T.Takahashi Hiroshima Univ. 26 May 2008 NanoBeam 2008.](https://reader035.fdocuments.in/reader035/viewer/2022062305/5697bfac1a28abf838c9b3eb/html5/thumbnails/1.jpg)
T.Takahashi Hiroshima
Optical Cavity R&D for Photon Colliders
T.Takahashi Hiroshima Univ.
26 May 2008NanoBeam 2008
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Contents
• Brief Introduction– laser and cavity for the PLC
• A design of the cavity for the PLC– Design study of an optical cavity for a
futurephoton-collider at ILC• G. Klemz a,b,, K. Meonig a, I. Will b,
• Cavity for the PLC and Related Activities• Possible R&D?
Recent activity document PLC technology being preparedJ. Gronberg, T. Omori, A. Seryi, T. Takahashi, V. Telnov, J. Urakawa, A. Variola, M. Woods
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Principle of the Photon Collider
e beam e beam
laser
laser
cp ip
Convert almost all electrons to high energy photons by Compton scatteringspecification of the electron beam: fixed (tuned to the PLC)
a few mm
Requirement for the lasers
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T.Takahashi Hiroshima
Photon Collider issues
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T.Takahashi Hiroshima
Photon Collider issues
many issues but
manpower, money may
solve
do it now! but less
expensive
too soon to be discussed
most unknownneed demostration
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T.Takahashi Hiroshima
Lasers for Photon Colliders
• have to meet requirement of;– ~5J/pulse, 1-3ps pulse duration
• ~2TW pleak power
– ~300ns separation 3000bunches/train
– 5Hz• ~70kW average power
– O(10m) focusing – timing ~1ps– polarization
5 300050
1 (0.3)
JHigh pumping power MW
ms eff
Too big to be built by single laser system
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T.Takahashi Hiroshima
Ideas to reduce laser power• RING (Recirculation Injection by Nonlinear Gating)
Cavity (Gronberg LEI2007)
• Pulse Stacking Cavity
transmit 1 ,reflect 2
Recirculation of a laser pulseto reduce average laser power
Stack laser pulses on phaseto reduce peak as well as averagepower
Klemiz, Monig
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RING cavity at LLNL
T.Takahashi Hiroshima
Integrated energy is28.5 times that of a singlepulse
I. Jovanovic,et.al
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The RING system has been demonstrated and published, joule-scale demo next year
T.Takahashi Hiroshima
Gronberg LEI2007
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Pulse Stacking Cavity
K. Moeing
•total length ~100m•all mirrors outside
the detector•Enhancement O(100)
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an ideaKlemiz, Monig
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detector w/ cavity
T.Takahashi Hiroshima
Klemiz, Monig
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some points of design
T.Takahashi Hiroshima
~15m
Size of mirror -> as small as possible to reduce cost, weight
smller spot size high laser photon density -> high Compton eff. larger divergence -> larger mirror
larger crossing angle->lower total photon yield
to be optimized for luminosity
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an optimization
T.Takahashi Hiroshima
~15m
0.75 2
120
gauss
cm
2
22r
I e
6.5 14.3CP m m 2 160 6.5gauss CPcm for m
53mr
9 / , 1.5 ( )J pulse ps
34 2 11.5 10L cm s
Klemiz, Monig
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miss alignment of mirrors
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control of circumference
T.Takahashi Hiroshima
max max
max
1 1( )
21 sin 1 2 sin
A A AF
A
[ ]nm
max/A Afor Amax = 100
max
max
0.6 / 0.9
1.7 / 0.5
nm for A A
nm for A A
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Requirements for the PLC cavity
• pulse stacking– enhancement ~ 100
• focusing laser spot ~ (10m)• keeping circularly polarized laser• synchronized with electron bunch (<ps)• high vacuum at around the IP
– not allowed to affect e beam ~ O(10-7 P)
• large scale – -circumference ~ 100m±(<nm)
• high power– O(10J)/pulse, ~2TW, ~70kW
T.Takahashi Hiroshima
~PosiPol
O(m)
~g wave
CW
unprecedented
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PosiPol R&D KEK LAL
type 2 mirrors FP 4 mirrors ring
enhancement 1000 10000
Laser spot size 30m 15m
Feed back Analog PID digital
e-at ATF, to get experiences with e-beam
stand alone
(new w/ e- beam being designed.
to be at ATF)
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initial performance of the cavityin ATF ring
T.Takahashi Hiroshima
laser pulses
L
transmitted pulses
power enhancement ~200
laser focused to 30m
performances consistent w/ parameters
in ATF environment
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photon generation
T.Takahashi Hiroshima
relative position: laser – electron bunches
num
ber
of p
hoto
ns
trail of laser-electron collision
relative timing: laser – electron bunches
sign
al f
rom
det
.
ray from laser-electron collision
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Cavity for the PLC is,,,Cavity for the PLC = Posipol, Laser wires,X-ray
+ large (like gravitational wave detector)
+ high power in cavity (unique for the PLC)
T.Takahashi Hiroshima
learn/collaborate from/with ILC relatedacitivities
what about PLC dedicated R&D
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Issues for large cavity
• A small one– posipol cavity is one piece
• other cavities such as in mode locked laser– on the table
• 100 m long cavity – need to align totally independent mirrors
• similar to gravitational wave exp. TAMA, LIGO etc.
T.Takahashi Hiroshima
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g- wave look like
T.Takahashi Hiroshima
Laser
Interfering beam
Beamsplitter
Suspended Mirror
Detector
dose not fit to the detector,,,,
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Optical system of TAMA300
do not want this one either,,,,,hope it is not necessary
R&D for feed back and support system for independent mirror arrangement.
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T.Takahashi Hiroshima
Step by step plan?
1. Cavities for Compton based pol. e+ projects– Fabry-Perot type spherical mirror– Fabry-Perot type off-axis parabolic mirror
2. Going to large scale – CW laser– independent mirror control
3. 1-2m scale ( with ATF bunch) – pulse laser (low energy)– independent mirror control
4. Cavity w/ high power laser at ATF2-IP– not possible at ATF-DR as high power laser is
destructive target
42cm
1~2m
ATF-DR
Lab->ATF-DR if possible
ATF2
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T.Takahashi Hiroshima
ATF-Layout
Lasers
ATF2 beamline
ATF-DR
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T.Takahashi Hiroshima
Ring cavity at ATF-DR-after we learn a lot from PosiPol cavities-
1m
50mr
circumference 4.62m (15.4ns)ー >64.9MHz
For 154ns spacing: 1/10 scale (15.4ns)
Lasers
10W mode locked,,,154nJ/pulse->15.4J/pulse w/ 100 pulse stacking
2400/xing
very similar to PosiPol experiment
A laser pulse hits once in 10 turns
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T.Takahashi Hiroshima
Ring cavity+High power at ATF2-IP
1m
50mr
64.9MHz ×50mJ=3.245kW
Cavity can be the same as ATF-DR but the laser is not
Average power = 50mJ×20×repetition = as low as 1W (or less)
we want 50mJ/pulse for the laser(5J/pulse in cavity)
Continuous pumping (64.9MHz)of the cavity is not wise: just for 20 bunches (for a train)
Peak laser pumping power = 50 20
3.31 (0.3)
mJkW
ms eff
need mini-Mercury amplifier?
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What we can do at ESA?
T.Takahashi Hiroshima
ESA ATF/ATF2
e beam 12 GeV 1.3 GeV
up to 12Hzsingle bunch
A few Hz154 ns x 30 bunches
very stablesub ps
s 2 GeV 10MeV
falicity large enough for 100 sale cavity?
No enoun space for large cavityregulation for the radiation safe
comment 10MeV facility for pol e+ etc? physics w/ intense field
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Summary
• Role of the PLC is yet to be studied– wait for the LHC, initial run of the ILC e+e-
• tehcenical issues should be studied– get it ready when needed
– interest in high flux g ray generation• a part of laser-electron int. community
• designs of the cavity exits– should see technical feasibility
• much can be learned from on going project– Posipol, Lawer Wires, X ray sources g wave detectors
• PLC dedicated study to be considered– a lot of issue to do with small scale program
T.Takahashi Hiroshima
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R&D feasible?
• A plan to construct high power laser system at the ATF2– proposal submitted
• A budget request for quantum beam technology– see Urakawa san for detail
T.Takahashi Hiroshima
some projects around laser science are being started
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R&D
T.Takahashi Hiroshima
J. Gronberg et. al
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Summary
• Role of the PLC is yet to be studied– wait for the LHC– initial run of the ILC e+e-
• get it ready when needed– cavities are one of the most unknow part
• much can be learned from on goring project– Posipol, Lawer Wires, X ray sources– gravitational wave detectors
• need to start PLC dedicated study by,,,,• collaboration with other acvityies
– dedicated study for feed back system, mirror alignment can be started as relatively low cost project
T.Takahashi Hiroshima
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summary
T.Takahashi Hiroshima
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Summary• Two Ideas of cavities to reduce laser power
– RING• technically easier but moderate power reduction
• R&D at LLNL for x ray sources
– Pulse Stacking• reduce both peak and average power ~(100) but very challenging
• R&D for PosiPol at KEK-ATF
• Laser technology continues to improve without our involvement but need an effort to meet design for cavities
• still high power
• mode locked laser for stacking cavity?
• ray faclity at ATF2 and/or ESA possible?
T.Takahashi Hiroshima
•Still much to learn from other field but 100m long cavity is completely different world•need to setup dedicated R&D toward the large scale cavity and ray generation