136
Chapter 4. Accelerator
chosen to balance the total luminosity against the fraction of luminosity close to ECM and the detector
backgrounds due to beamstrahlung.
Item
Symbol
Center-of-mass energy
Linac repetition rate
Number of particles / bunch
Number of bunches / pulse
Bunch separation
Bunch train length
Bunch length
Beam power / beam
Unloaded gradient
Loaded gradient1)
Effective gradient2)
Average RF phase
Linac length / beam3)
Beam delivery length / beam
Total site AC power
Normalized emittance at DR exit
Normalized emittance at IP
Beta function at IP
Beam size at IP
Full crossing angle
Disruption parameters
Pinch enhancement factor
Average beamstrahlung parameter
Average energy loss by beamstrahlung
Number of photons / electron
Nominal luminosity4)
Peak luminosity4)
1)
2)
3)
4)
ECM
frep
N
nb
tb
n b tb
σz
PB
EN L
EL
Eef f
φ
γx /γy
γ∗x /γ∗y
βx∗ /βy∗
σx∗ /σy∗
θc
Dx /Dy
HD
Υ
δB
nγ
L0
L
Value
Stage II
1000
100
0.75
192
1.4
268.9
110
8.65
11.53
64.8
49.8
44.1
11
7.25
14.11
1.9
233
300
3.0 / 0.02
3.6 / 0.04
3.6 / 0.04
8 / 0.11
13 / 0.11
243 / 3.0
219 / 2.1
7
0.16 / 13.1 0.10 / 10.3
1.49
1.42
0.13
0.28
4.6
7.5
1.26
1.30
17.7
18.5
25.0
25.0
Stage I
500
150
Unit
GeV
Hz
×1010
ns
ns
µm
MW
MV/m
MV/m
MV/m
deg
km
km
MW
×10−6 m·rad
×10−6 m·rad
mm
nm
mrad
%
×1033 cm−2 s−1
×1033 cm−2 s−1
Includes single- and multi-bunch loading.
Includes cos φ and 8% overhead for BNS, failure and feedback.
Includes diagnostics sections.
L0 = frep nb N 2 /4πσx∗ σy∗ .
Table 4.1: Overall parameters for JLC, based on the X-band main linacs.
In the initial stage (Stage I), ECM is assumed to be 500 GeV with a luminosity of 2.5 × 1034 cm−2 s−1
JLC Project Report, Revised, March 12, 2003, 3:21 P.M.