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