Accelerator Tuning

Good Tune Used for good Scan

By Dr. Kim

Solenoid 1	6.8 A
Solenoid 2	10.4 A
Gun Ver	-0.2 A
Gun Hor	+0.4 A
Output Hor	-1.4A
Output Ver	-0.5 A
Gun HV	+9.75 (Knob Setting)
Gun Grid Voltage	5.25 (Knob Setting)
RF frequency	2855.816 MHz
Modulator HV Power Supply	4.42 (Knob Setting)
RF macro Pulse Length (FWHM)	200 ns
Peak Current on FC	37.2 mAmps
Scope on FC
e- Beam Energy	14 MeV

Calibration

image	OTR image	cal_h (mm/px)	cal_v (mm/px)
		0.04308	0.04204
		0.04320	0.04228
		0.04349	0.04181
		0.04323	0.04196
		0.04337	0.04212
		mean (mm/px)	mean (mm/px)
		[math] 0.04327 \pm 0.00016 [/math]	[math] 0.04204 \pm 0.00018 [/math]

Results

Q1

At lower current background subtraction gets worse, because singal/noise drops.

42 mA, Positive Current, X projection

emit=0.388 +- 0.008 mm*mrad, emit_norm=10.64 +- 0.22 mm*mrad

beta=1.285 +- 0.024, alpha=0.94 +-0.03

parabola fit for x-projection:

In m unit y = 3.69167*10^(-6) -3.89000*x*10^(-6) + 4.79738*x.*x*10^(-6)

In mm unit

y = 3.69167 -3.89000*x + 4.79738*x.*x

//K1*L(1/m)   er K1*L    sgima^2(mm)   er sigma^2

Media:2011_Mar_Emit_fit_data_x.txt

Data created from parabola fit

Media:2011_Mar_Emit_data_from_fit_x.txt

42 mA, Negative Current, Y projection

emit=0.266 +- 0.018 mm*mrad, emit_norm=7.30 +- 0.50 mm*mrad

beta=0.918 +- 0.068, alpha=0.19 +-0.06

parabola fit for y-projection:

y = 2.81806*10^(-6) + 0.52202*x*10^(-6) + 2.35025*x.*x*10^(-6)

//K1*L(1/m)   er K1*L    sgima^2(mm)   er sigma^2

Media:2011_Mar_Emit_fit_data_y.txt

X and Y emittances are different. The parabola in X reaches min around 0.4, while in Y reaches around 0.15. Which suggests quadrupole strengths of X and Y are way different for same coil current. Which might suggest beam is not centered, because when beam is off-centered we have this can occur.