Medium and High Energy Photons for Nuclear Particle
Physics
Schin Daté Accelerator Division, SPring-8/JASRI
Advanced Photons and Science Evolution 2010 June 14-18 , 2010, Osaka Japan
Previous talks which includes laser backscattering
beamlines
T. Shima: New Subaru
Y. Ohashi: LEPS/LEPS2W. Tornow: HISW.C. Chang: LEPS
M. Niiyama: LEPS/LEPS2
My talk:
I. High Energy Production in SPring-8
II. Intense 10 MeV Production in Light Sources
Additional options to future backscattering beamlines
Production of high energy gamma rays
HELP production by X-ray re-injection
multilayer mirror
Choice of Undulator
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K = 0.934 × B0[T]λ 0[cm]
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100 eV = ω1(0) = 4πβhcγ 2 /λ 0
1+ K 2 /2
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Ptot ~ Nγ 2K 2 /λ 0
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K 2
(1+ K 2 /2)2Portion of the fundamental=
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λ0 <1 m
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K = 3
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λ0 =1.1 m
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⇒
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B0 = 300 kG
Yield of X-ray photons
†
d˙ N ph
d /I
e(
)
Re-focussingThin undulator approximation
e-
275x2 m
6x2 m
~100 rad
Can s be
€
5×10−3 mm2 ?
In principle, yes.
spherical mirror
Bunch mode dominance
. . .100 rad
60 cm
h ~ 275 m
e-
v ~ 6 m
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60cm/2 ×100μrad = 30μm
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Nγnext ~ σ
aph
~ Nγmain
5
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Nγall ~ 1.75Nγ
main
Yield of High Energy Gamma
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L=neN ph
sRfbunch
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€
I 1 ≡ Nph
1 ⊗σ
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N ph = neN ph
1Notation: ,
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I 1 =10−2 b
Undulator (K=5~6, λ =1.1 m, 4 periods)
: reinjection efficiency
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R
for
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Eγ = 4 - 6 GeV
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⇒
Electron beam emittance + re-focussing
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s = 5 ×10−9 m2
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εx = 3.4 ×10−9 m⋅rad( )
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⇒
Beam current: 100 mA/e
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ne fbunch =
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⇒
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( ≈ )
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Nγ ≈106 /s.
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Nγ = L ⊗σ ,.
50%
Summry of part IProvidedan undulator with high reflectable (R > 0.5)spherical mirror for 100 eV photonswith timing adjustment system (mirror position z = 24 +- 2 m, dz = 6mm)
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N p = 4, λ 0 =1.1m, B0 = 300 kG − 600kG
We may obtain
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˙ N γ =106 /s
in principle. The number may increase by an order of magnitude forthe future refinement of the storage ring.
Intense 10 MeV Production in Light Sources
II
Well known facts about Compton back scattering
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E e
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εL
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Eγ
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θ
Controlled Polarization(3)€
dσdEγ
~ flat(1)
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εL ≤ Eγ ≤ Eγ max ≈ 4γ e2εLEnergy ,
Angle
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θ =θ(Eγ )
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<θ 2 >≈1/γ e2(2) ,
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˙ N γ = 2.1×107(s−1)σ [b]I[A]λ L[μm]l[m]PL[W ]/sL[mm2]
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=1.34 ×108(s−1)PL[W ]
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σ = 0.5 bI = 100 mA
l = 10 m
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sL = π (0.5 mm)2
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λL =10 μm
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for
Yield(4)
Progress in laser technology
Heat load limit ~ 20 MW / mm 100 kW output is cleared in this way
bundled fiber line of, say, cm is possible to make
Fiber Laser
Sing
le m
ode
CW
out
put p
ower
(W)
year
15m core
Yb fiber laser (IPG): 1030 ~ 1050 nm CW single mode 2 kWmultimode 20 kW
Polarization?
Eg_max for CO2
2. Production of Intense 10 MeV Rays
(1) Enegy aperture
Spring-8 CLS DFELL MAX-IV NSLS-II
8 2.9 0.24-1.2 3 3
2436 285 64 96 1320
16 0.876 42 keV 0.712 0.816
4/3 2.74 17.1 1.7 4.04
154 4519 @ 500 MeV30 @ 1.2 GeV
91 91
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E0 [GeV]
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h
€
α
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U0 [MeV]
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q
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δEmax[MeV]
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1.68 ×10−4
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3.8 ×10−3
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8.6 ×10−3
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7.45 ×10−4
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3.7 ×10−4
(2) Longitudinal beam quality
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˙ N γ =
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1011
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s−1
I = 100 mA
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⇒
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Pγ / e− pass =10−7
Spring-8 CLS DFELL MAX-IV NSLS-II
4.8 0.57 0.36 0.96 2.6
4.2 1.9 4.3 4 9.7€
T0(μs)
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α s−1(ms)
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107T0 >> α s−1
No serious effect on the longitudinal beam quality
Summary of Part II
There is no crucial problem to producee very intense (~ 10^11 /s) 10 MeV gamma rays in 3 GeV light sources including CLS, MAX IV and NSLS-II..There are technologies available to realize the intense gamma production.Now is the adequate time to consider such a possibility seriously.
Conclusion
I. We may think seriously about quasi-monochromatic g beamline with Eg_max ~ Ee and Ng ~ 10^6 /s as an option to future beamlines in highenergy synchrotron light sources.
II. There is no crucial problem to producee very intense (~ 10^11 /s) 10 MeV gamma rays in new 3 GeV light sources.
-------- Backup --------
reinjection schemes
Why Do We Want 10^11 /s Photons?
= 10 g / cm^3
Because many interesting elementary interactions occur with σ ~ pb
l = 1 cm
σ = 1 pb €
N l = 6 b−1
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⇒
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⇒
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˙ N γσρl = 0.6 s−1
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˙ N γ = 1011 s−1for
S P r i n g8
Old proposal
Optical param bl33
optical parameters
beam divergence
<σ x’ >BCS ~ 64 rad beam divergence in LSS BL is dominated by Compton scattering.
εx = 3.4
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×10-9 rad
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⋅mεy
εx, = 0.2 %( )
<=
33LEP LSS<σ x’ > [rad]
58 23
<σ y’ > [rad]
1.8 1.2
<σ x > [mm] 0.34 0.30<σ y > [m] 12 12
<=>
Contributions are wighted for Gaussian laser beam.Values are valid for the laser waist radius > 0.5 mm.
Angular Distribution
Polarization
Energy
E (GεV)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
00 .5 11 .522 .5 3
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