Multiple Partial Siberian Snakesin the AGS

Junpei Takano

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

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

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

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

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%

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

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( )

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

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

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

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.