Spin Tune as function of snake orbital angleMarch 31, 2009

Mei, Vadim, Thomas

Orbit angle in snakes

APEX: ramp 2

APEX: ramp 1

operation

300 murad angle -> 0.046 spin tune shift at 250 GeV

Snake angle in present operation

At 9 o’clock the zero orbit angle at snake location leads to few mm excursion at a neighboring location.In both rings.

Spin tune shifts

12

21 22

1

co_snco_snco_snco_inco_outco_rti

co_snco_rtco_rtsp

xxxΔ;xxxΔ

xΔxΔxΔπ

Gδν

Spin tune shift due to snakes:energy dependence(Waldo’s calculations)

Due to rotators at snakes. Strong energy dependence.

At injection

With no change of snake angle

With -0.3mrad change of snake angle

With 0.3mrad change of snake angle

With no change of snake angleWith -0.3mrad change of snake angle

With no and -0.3mrad change of snake angle

At Store: pp93, snake angle -0.3 mrad

Polarization transmission w.r.t. snk angle

Snake angle[mrad]

Blue at injection

err Blue at store

err Yellow at injection

err Yellow at store

err

-0.3 58.4 3.7 53.8 3.7 63 3.2 16.4 4.2

-0.3 50.2 5 35.5 3.8

0.3 66.4 3.8 55.2 5 59.7 3.2 48.5 3.7

• Indication of Blue spin tune at injection is further away from 1/2 with no change of snake orbital angle

• -0.3mrad snake angle at injection in Blue seems to push the spin tune either close or further away from 1/2

• +-0.3mrad snake orbital angle change along the ramp:– Yellow shows difference in polarization transmission– Difference in Blue is not so clear . Spin tune close to ½ (?).

Conclusions