Acceleration of the polarized proton beam in the AGS with multiple partial Siberian snakes
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Transcript of Acceleration of the polarized proton beam in the AGS with multiple partial Siberian snakes
Acceleration of the polarized proton beam in the AGS with multiple partial Siberian snakes
Junpei Takano
1. Spin Physics
We have “the proton spin crisis”.Proton spin is not equal to “two up quarks” + “down quark”.
The proton spin depends on the gluon??
up quark
down quark
gluon
Proton spin
BNL has the polarized proton accelerator complex.
RBRC researches the polarization of the gluonfrom this high energy polarized protons collision.
1. Spin Physics
BRAHMS & PP2PP (p)
STAR (p)PHENIX (p)
AGS
LINAC BOOSTER
Pol. Proton Source500 A, 300 s
Spin RotatorsSolenoid Snake
Siberian Snakes
200 MeV Polarimeter
AGS pC CNI PolarimeterAC Dipole
RHIC pC Polarimeters
Absolute Polarimeter (H jet)
RHIC
Siberian Snakes
Cold Snake
Warm Snake
2. Acceleration of polarized proton beam
LINACBOOSTERPol. Proton Source
500 A, 300 s
200 MeV Polarimeter
2. Acceleration of polarized proton beam
80% polarized proton is provided
No depolarization in this sections
BRAHMS & PP2PP (p)
STAR (p)PHENIX (p)
Spin Rotators
Siberian Snakes
RHIC pC PolarimetersAbsolute Polarimeter (H jet)
RHIC
Siberian Snakes
2. Acceleration of polarized proton beam
All depolarizing resonances are overcomeby Full (100%) Siberian Snakes
AGSSolenoid Snake (5%)
AGS pC CNI Polarimeter
AC Dipole
Cold Snake (1.5~2.5T, 5~15%)
Warm Snake (1.5T, 5.89%)
2. Acceleration of polarized proton beam
AGS Partial Snakes
AGS has imperfection res. and intrinsic res.
Imperfection res.νs (spin tune) = Gγ = integerwhere G = (g-2)/2 = 1.7928 in the proton case
Weak partial snake is enough to overcomebefore 2004: solenoid snake → Coupling res.after 2004: warm snake
Intrinsic res.νs = Gγ = kP±νy
where k is integer, P is super periods (P=12 for AGS),νy is vertical tune (~8.95 in AGS)
by using AC dipole or strong partial snakecold snake was installed in 2005
Coupling res.νs = Gγ = kP±νx (νx=8.6 in AGS)
3. Siberian Snake for overcoming depol. res.
Warm Snake2. Acceleration of polarized proton beam
Cold Snake2. Acceleration of polarized proton beam
Formula of spin tune and Siberian snake strengthcosπνs = cos(δ/2) cosπGγwhere δ is the angle which snake can tilt
3. Siberian Snake for overcoming depol. res.
3. Siberian Snake for overcoming depol. res.
0 10 20 30 40 504
6
8
10
12
14
16
18
20
22
24Sn
ake
stre
ngth
[%
]
G
CSNK_1.5T CSNK_2.0T CSNK_2.5T SSNK WSNK
Snake strength of the AGS partial Siberian snakes
Snake strength depends on the beam energy.
Injection Extraction
20 25 30 35 40 45 50-0.002
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014A
sym
met
ry
G
RUN4 RUN3
36+v
48-v36-v 24+v
12+v
-7.2% +1.5% +4.6% -0.5% -8.2%
-17.5%-8.3%-6.9%-13.4%N/A
RUN4
RUN3
3. Siberian Snake for overcoming depol. res.
3. Siberian Snake for overcoming depol. res.
Total asymmetry drop at the intrinsic res. In RUN4 = -1.6%Total asymmetry drop at the intrinsic res. In RUN3 = -46.1%
Polarization at the AGS flat top in RUN3 = 40%Polarization at the AGS flat top in RUN4 = 50%
The warm snake increases the polarization 25%
Results of RUN4
Locations of the snakes in the AGS
Cold Snakeat A20
Warm Snake at E20
4. Double partial snakes scheme
1/3 of the ring
Merit 1: making the spin tune gap bigger at the intrinsic resonances
Merit 2: decreasing the spin mismatch at the injection and extraction
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
37 38 39 40 41 42 43 44 45 46 47Ggamma
spin
tun
e
WSNK+CSNKWSNKIntrinsic res.
4. Double partial snakes scheme
Large spin tune gap Gγ= 3k k: integerIntrinsic res. νs = Gγ= 12k±νy
48-νy 36+νy
WSNK=6%CSNK=10%
Extraction energy
Large spin tune gap
4. Double partial snakes scheme
Spin tune around injection energy and first intrinsic resonance
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=16%
0+νy
Injection energy
Large spin tune gap
4. Double partial snakes scheme
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
WSNK = 8.4%
Spin mismatch
Injection energy
Vertical component at L20 = 0.991
SSD at Ggamma=46.5
-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
Vertical component at H10 = 0.996
Spin mismatch
WSNK = 6% Extraction energy
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 = 16% Injection energy
Vertical component at L20 = 0.969
SSD at Ggamma=46.5
-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 = 10% Extraction energy
Vertical component at H10 = 0.988
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 = 16%, WSNK = 8.4% Injection energy
Vertical component at L20 = 0.992
SSD at Ggamma=46.5
-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 = 10%, WSNK = 6% Extraction energy
Vertical component at H10 = 0.998
4. Double partial snakes scheme
Ver. comp. WSNK1.5T CSNK2.5T W1.5T+C2T
Injection 0.991 0.969 0.992
Extraction 0.996 0.988 0.998
WSNK only: small spin mismatchCSNK only: spin mismatch comes worseWSNK + CSNK: small spin mismatch
Stronger CSNK makes spin mismatch bigger.
Cold Snake Strength (%)
0 5 10 15 20 25 30 35
Asy
mm
etry
(*1
0-3)
52
54
56
58
60
62
64
66
Asymmetry at Gγ=4.5 (Injection energy)
5. Results of RUN5
Calculated curve
Spin mismatch were measured at injection energy
5 10 15 20 25-0.10
-0.05
0.00
0.05
0.10R
aw A
sym
met
ry
Ggamma
RUN4(WSNK+ACdipole) RUN5(WSNK+CSNK2T) RUN5(CSNK2.5T)
12+v
0+v
5. Results of RUN5
Effect of AC dipole
25 30 35 40 45 50
-0.02
-0.01
0.00
0.01
0.02R
aw A
sym
met
ry
Ggamma
RUN4(WSNK+ACdipole) RUN5(WSNK+CSNK2T) RUN5(CSNK2.5T)
36+v
36-v
5. Results of RUN5
Effect of AC dipole
CSNK15%
WSNK5%
CSNK10%
WSNK5%
CSNK15%
WSNK0%
AC dipole
WSNK5%
_x ( mm-mrad) 12 11 13 25
_y( mm-mrad) 13 15 13 10
Vert. aperture limit No No Yes Limited at 0+
Hori. aperture limit Yes Yes No No
Polarization 52.5% 56.4% 55.1% 57.6%
Intensity (1011) 0.4 0.7 1 1
Difficulty intensity intensity Raise Qy 0+ V. aperture
5. Results of RUN5
All intrinsic resonances are overcome by the Cold Snake without AC dipole
5. Results of RUN5
2002 2003 2004 20050
10
20
30
40
50
Pola
riza
tion
[%
]
2002 2003 2004 20050
100
200
300
400
500
600
Figu
re o
f M
erit
(L
P4 )
Polarization in RHIC100GeV vs. 100GeV
AGSSolenoid Snake (I10)
Cold Snake (A20) Warm Snake (E20)
If the Solenoid Snake is movedfrom I10 to I20....
6. Three partial snakes scheme
6. Three partial snakes scheme
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
CSNK = 16%, WSNK = 8.4%, SSNK = -7.6% Injection energy
No spin mismatch
6. Three partial snakes scheme
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
6. Three partial snakes 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 current should be turned to positive for making spin tune large, but the bipolar PS is needed in this case.
6. Three partial snakes scheme
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.
CSNK=16%WSNK=8.4%SSNK= 10%
Large spin tune gap
Injection energy
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
40 41 42 43 44 45 46 47
Ggamma
spin
tun
e WSNK+CSNK+SSNKWSNK+CSNKWSNKIntrinsic res.
6. Three partial snakes scheme
CSNK=10%WSNK=6%SSNK= 4%
Large spin tune gap
Extraction energy
7. Summary
Warm Snake has been installed in RUN4 Polarization was improved to 50% at extraction of AGS
Cold Snake has been installed in RUN5 2snakes scheme had been worked All intrinsic resonances are overcome by Cold Snake Spin mismatch at injection was measured
3snakes scheme for no spin mismatch was calculated3snakes scheme can help the spin tune gap larger
Special thanks
L. Ahrens, M. Bai, E. D. Courant, J. W. Glenn, H. Huang, F. Lin,A. U. Luccio, W. W. MacKay, T. Roser, N. Tsoupas, J. Woodsand all members in Main Control Room in BNL
M. Okamura / RIKEN
T. Hattori / TITECH