Post on 20-Jan-2016
description
Parameter Choice for ILC(Very Low Charge Case)
J. Gao
IHEP -ILC Collaboration
IHEP, Beijing, China
ILC-Aisa Collaboration Meeting, KEK,
March 24, 2005
Content
1) Design philosophy
2) Parameter relations
3) Parameter proposal for ILC from IHEP, China
4) Conclusion
ILC Design Philosophy
Required Colliding energy, luminosity
1) Backgroud noise (low) and beam quality (good)
2) Operational condition (stable)
3) Technical constrains (realisable)
4) Damping ring (small space charge
effect, reasonable circumference...)
5) Total AC power (reasonable)
Parameter Relations (1) 2
4rep b e
Dx y
f N NL H
Luminosity
Disruption parameter ,,
2
( )e e z
x yx y x y
r ND
3 22( )
3e e
Bx y z
r NF R
Beamstrahlung inducedEnergy spread
x
yR
F(R>>1)=1.3/R
Parameter Relations (2)
2 e e
x
r Nn
2
21
4e x
Had D Hadx y
NN H n
35 24.2 10Had m
er
eN
Classical radius of electron
Particle population inside a bunch
R>>1
Parameter proposal for ILC from IHEP, China (1)
-Wcm=500GeV
-
-Beamstrahlung energy spread
-Mean number of beamstrahlung photons per
Electron
-Number of hardronic events per crossing
34 2 12 10L cm s 0.03B
0.8n
0.125HadN
(Low background noise)
Parameter proposal for ILC from IHEP, China (2)
-Disruption parameter
-R=103 (flat beam)
- low charge is good for many things
9yD 1.5DH
(Operational stable, small kink instability)
96 10eN
Parameter proposal for ILC from IHEP, China (3)
-
-
-
-
-
-
41.2 10z m 73.1 10x m 93 10y m
8, 2.72 10n y m rad
6, 3.74 10n x m rad
0.012x m 41.6 10y m
(m·rad)
(m·rad)
Parameter proposal for ILC from IHEP, China (4)
-
-
- If
-*
-
-
*Assuming damping ring’s circumference is 17km.
44.3 10rep bf N 10.26bP MW
8rep zf H 5375bN 150bunch seperationT ns
6.45beamI mA0.8beamT ms
Parameter proposal for ILC from IHEP, China (5)
-Damping ring Length Ld=17km-Ed=5GeV, damping time -Bunch length inside the damping ring:
-Space charge tune shift (y):
96 10eN
, 8z d mm
3 / 2 1/ 2 2 2, , ,
, (2 ) ( )e e d
n x n x d z d
r N Lsc y
,| | 0.075sc y
28y ms
Space charge problem is solved by parameter choice!
Parameter proposal for ILC from IHEP, China (6)
Space charge tune shift
Particle survival ratio at the ejection
Parameter proposal for ILC from IHEP, China (7)
Beam current
Beam pulse length 0.8ms
Peak power per cavity (Eac=35MV/m) 234kW
( , or over coupling factor 1.72 with )
Fill time 0.536ms
Rf pulse length 1.34ms
6.45bI mA
63.16 10extQ 90 6 10Q
100 1 10Q
Parameter proposal for ILC from IHEP, China (8)
Total AC power is around 100MW
Conclusion
1. Compared with Tor Raubenheimer’s parameterlists (5 lists for 500GeV case including low Q case), the ILC parameter proposed by IHEP can benamed “Very Low Q” (VLQ).2. VLQ has low IP background noise, operationally stable, large misalignment tolerance, … 3. The space charge problem in the damping ringscan be intrinsically eliminated by this parameter choice.4. There is no fundamental technical limitations
Thanks
谢谢