IP BPM’s for ATF2 Vladimir Vogel KEK May30, 2005 Third Mini-Workshop on Nano Project at ATF
z = 5 mm z = 2 mm z = 8 mm BPM frequency (Hz) BPM relativity resolution z = 0.3 mm
The purpose of the bunch length shorting in ATF DR is: - to increase the sensitiveness to the beam offset, which will be worse when we will do shorter the sensor cavity length to reduce the beam angle sensitivity. - to start study how the BPM work with short bunch length. - study the interaction of high order modes and the working mode in the sensor cavity.
Frequency (GHz) Pout Y out X out Electric field in the sensor cavity Rv.t.=8mm Rv.t=6mm Rv.t=5mm BINP BPM’s X – Y coupling -40 ~ -50 db ATF2 IP BPM’s X-Y coupling Less than -80db (expected)
Reduction of the angle sensitivity, in the assuming that the signal proportional to the beam angle is equal to the signal from beam which has a 1 nm position displacement Sin Cos The beam angle signal has phase difference 90 degree to the signal of the beam offset, We can use this fact! If Sin( ) and Cos( ) outputs will give us only 20db isolation, we can get enough reduction of the angle sensitiveness. Beam angle measurement in ATF extraction line. BINP cavity#4, 2001 Cavity effective length (m) Reduction of angle sensitivity BINP ATF2 F=6426MHz F=9000MHz Sin position Cos angle referencesensor
Q=1*10^10, Zload=50 Ohm, ^-9 m, z = 8 mm Thermal noise (dF=3 MHz, T = 300K) 1.57 V Qload=1500 Frequency (GHz) BINP BPM Leff =7mm Dtube =5mm BPM output voltage (V)
Block diagram of the BPM’s electronic for IP BPM 1.One reference cavity 2.Six sensor cavity
Method of determination the BPM resolution 1.Three BPMs for Y and X: nm step mover 3. Beam movers and two steering magnet in the fix distance
Welded bellows IRIE KOKEN CO., LTD NS122-1, Dmax=22mm Dmin=8mm L from 7 to 17 mm +2*3mm VLEPP type vacuum connectors F TM110 = 9 GHz, Leff. = 7 mm = 2.0 Resolution 1-2 nm Angle sensitivity To 1 nm –200 rad IP BPM’s setup for Y position measurement Temperature control