Multiple Partial Siberian Snakes in the AGS
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Transcript of Multiple Partial Siberian Snakes in the AGS
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Multiple Partial Siberian Snakesin the AGS
Junpei Takano
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BRAHMS & PP2PP (p)
STAR (p)
PHENIX (p)
AGS
LINACBOOSTER
Pol. Proton Source500 mA, 300 ms
Spin Rotators
Solenoidal snakefor imperfection res.but produce coupling res.Achieved P=40% in 2003
SuperconductingSiberian Snakes
RHIC pC PolarimetersAbsolute Polarimeter (H jet)
RHIC
SuperconductingSiberian Snakes
Cold snake for imperfection res. and intrinsic res. Achieved P=65% in 2006 with Warm snake
Warm snake for imperfection res. Reduced coupling res. Achieved P=50% in 2004 and P=55% in 2005
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0 10 20 30 40 504
6
8
10
12
14
16
18
20
22
24
Snak
e st
reng
th [
%]
G
CSNK_1.5T CSNK_2.0T CSNK_2.5T SSNK WSNK
Snake strength has energy dependence
Injection Extraction
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Merit 1: large spin tune gapMerit 2: small spin mismatch
Double snake scheme
1
2: CSNK strength
: WSNK strength
A20:CSNK E20:WSNK
AGS
to RHIC
from Booster
120°
)}cos(2
{coscos1 1
Gsp
)}3
cos(2
sin2
sin)cos(2
cos2
{coscos1 21211
GGsp
← Spin tune Eq. for “single” snake
↓ Spin tune Eq. for “double” snake
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
4 5 6 7 8 9 10Ggamma
spin
tun
e
WSNK+CSNKWSNKIntrinsic res.
WSNK=8.4%CSNK=15%
12k±νy (νy = 8.9)
Injection energy
Large spin tune gap
Spin tune around first intrinsic resonance with 2 snakes
= 3m
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Stable spin direction
-1.2-1
-0.8-0.6-0.4-0.2
00.20.40.60.8
0 10 20 30 40 50
AGS location
n_xn_yn_zmismatch
injinj ext
Spin mismatch
CSNK WSNK
CSNK@A20=20%, WSNK@E20=8%
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Coldsnake%
vertcomp
Pol. at injection
0 1.000 80.00
5 0.997 79.75
10 0.988 79.02
15 0.972 77.79
20 0.951 76.09
25 0.924 73.91
30 0.891 71.28
Without Warm Snake(Cold Snake only)
Coldsnake%
vertcomp
Pol at injection
0 0.992 79.37
5 0.999 79.91
10 0.999 79.96
15 0.994 79.52
20 0.982 78.58
25 0.965 77.17
30 0.941 75.27
With 8% Warm Snake(Double snake)
Snake strength at “injection” energy
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If the SSNK is relocated from I10 to I20....Spin tune gap will be larger.
)3
cos(2
sin2
sin)cos(2
cos2
cos2
{coscos1 213211
GGsp
)}3
cos(2
sin2
sin)3
cos(2
sin2
sin 1332 GG
SSNKI20←I10
A20:CSNK E20:WSNK
AGS
to RHIC
from Booster
1 2 3: CSNK strength : WSNK strength : SSNK strength( )
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
4 5 6 7 8 9 10
Ggamma
spin
tun
e WSNK+CSNK+SSNKWSNK+CSNKWSNKIntrinsic res.
Large spin tune gap
CSNK=16%
WSNK=8%
SSNK= 10%
Spin tune around first intrinsic resonance with 3snakes
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CSNK=15%, WSNK=8%, SSNK=-7%
Stable spin direction
-1.2-1
-0.8-0.6-0.4-0.2
00.20.40.60.8
0 10 20 30 40 50
AGS location
n_xn_yn_zmismatch
injinj ext
SSNKWSNKCSNK
Spin mismatch with 3snakes
No spin mismatch
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33100 33200 33300 33400 335000.00.20.40.60.81.01.21.41.61.82.0
Inte
nsit
y (1
e11)
run#
33100 33200 33300 33400 335000
1020304050607080
Pol
ariz
atio
n [%
]
Red: 10%CSNK+6%WSNKBlue: 6%CSNK+6%WSNK
Result in RUN6
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Summary
The triple snake scheme was simulated. ・ Larger spin tune gap ・ No spin mismatch
6%CSNK+6%WSNK was operated. Achieved same level polarization to 10%CSNK +6%WSNK
If the 6%+6% machine is optimized, the polarization might be improved.
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Extra slides
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SSD at Ggamma=4.5
-1.2-1
-0.8-0.6-0.4-0.2
00.20.40.60.8
11.2
AGS location
spin
com
pon
ent
n_x
n_y
n_z
C15 H10 L20L20 A20 E20C20
4. Double partial snakes scheme
Spin mismatch
CSNK = 24% Injection energy
Vertical component at L20 = 0.930
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SSD at Ggamma=4.5
-1.2-1
-0.8-0.6-0.4-0.2
00.20.40.60.8
11.2
AGS location
spin
com
pon
ent
n_x
n_y
n_z
C15 H10 I20 L20L20 A20 E20 I10C20
No spin mismatch
CSNK = 10%, WSNK = 6%, SSNK = 4% Extraction energy
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Operation of SSNK for triple snake scheme
0%
10%
injection
extraction
ramp upS
SN
K s
tren
gth
%
-7.6%
4%
The current at injection is negative for no spin mismatch.Then the sign should be turned to positive to open the spin tune gap larger, but the bipolar PS is needed in this case.