1. Update on MEIC Activities at ANL
Work done by P. Ostroumov1, Z. Conway1,
B. Erdelyi2 and B. Mustapha
1ANL, Argonne, IL 60439, U.S.A
2Department of Physics, NIU, DeKalb, IL 60115, U.S.A

2. Optimum stripping energy: 13 MeV/u
A Short Linac for MEIC
4.8 MeV/u
Optimum stripping energy: 13 MeV/u
10 cryostats
4 cryostats 2
Ion sources
QWR
HWR IH
RFQ
MEBT
10 cryos
4 cryos
2 cryos
Stripping to 208Pb61+ at 8.5 MeV
Proton: ~285 MeV
Lead (208Pb67+): ~100 MeV/u
Proton: ~120 MeV
Lead (208Pb67+): ~100 MeV/u
We asked P. Ostroumov at the last spring MEIC collaboration meeting to consider a short version of the ion linac for MEIC for achieving a substantial cost reduction but not compromising the performance
Peter has done it:
“The SC section of the linac is much shorter now. We will have normal conducting section up to 4.8 MeV/u, 1 cryomodule of QWRs with 9 cavities to reach 8.5 MeV/u for lead ions, stripping at 8.5 MeV/u to q=61 and additional 4 cryomodules with QWRs and HWRs. Total number of cavities =45. Proton energy=120 MeV, lead ion energy=40 MeV/u.
Expected cost saving: 2/3 of the present linac cost (~$150M)

3. Smaller (Race-track) Pre-booster
From P. Ostroumov’s quarterly report:
“The main goal of re-designing the MEIC pre-booster is to reduce its cost. We originally proposed to replace the figure-8 design by a more compact ring design cutting its circumference by about a factor of 2. The first design iteration showed that a square ring needs to be longer than the original design to avoid energy transition for a 3 GeV proton beam (γtr = 4.22). Switching to a hexagonal ring design, in the second iteration, showed that the transition energy condition could be satisfied for a 180 m long ring which is about ¾ of the original design circumference. In the current iteration, we moved to an octagonal ring design which satisfies the transition energy condition with a circumference of 120 m, that is about half of the original figure-8 circumference of 234 m. Limiting the ring circumference to 120 m, Table 1 shows a comparison of the design parameters for the different ring options; square, hexagonal and octagonal.

4. Straight section length, m 16.4 11 8.3 Maximum βx 18 15.6 15.3
Parameter
Square
Hexagonal
Octagonal
Circumference, m
120
Arc length, m
13.6 9
6.7
Straight section length, m
16.4 11
8.3
Maximum βx 18
15.6
15.3
Maximum βy 30
21.5
21.0
Maximum dispersion
11.6
6.6
4.2
βx at injection
14.9
5.9
6.0
Normalized dispersion at injection: D/√ βx
3.01
2.72
1.71
Tune in X
2.09
2.34
Tune in Y
0.90
1.22
1.18
Gamma transition
2.46
3.57
4.7
Gamma at extraction (3 GeV)
4.22
Momentum compaction factor
0.164
0.078
0.045
Number of quadrupoles 20 40
Quadrupole length, m
0.4
Quadrupole half aperture, cm 5
Maximum quadrupole field, T
1.5
Number of dipoles 24
Dipole bend radius, m 8
Dipole angle, deg 15
Dipole full gap, cm
Maximum dipole field
1.6