Vertical Beam Halo Study using Diamond Sensor. June 2015 ATF2 V. Kubytskyi, H. Guler, P. Bambade, ATF team 20/06/2015

Shifts Fri 5/29 Diamond Sensor http://atf.kek.jp/twiki/bin/view/ATFlogbook/Log20150529d Tue 6/9 http://atf.kek.jp/twiki/bin/view/ATFlogbook/Log20150609d Thu 6/11 YAG screen/ Diamond Sensor http://atf.kek.jp/twiki/bin/view/ATFlogbook/Log20150611s Wed 6/17 http://atf.kek.jp/twiki/bin/view/ATFlogbook/Log20150617o Fri 6/19 YAG screen/Diamond Sensor http://atf.kek.jp/twiki/bin/view/ATFlogbook/Log20150619o

1.3 Signals measured at ATF2 Total charge in the diamond 50 V 200 V 400 V BEAM Ch1 Ch2 Ch3 Ch4 10 waveforms at each position ch1 ch2 ch3 ch4

Scan procedure First Beam core scan @-400 V with 30dB attenuators. Find the beam position. Beam steering (horiz/vert) to maximize signal on given channel. Beam core scan @-400 V with 30dB attenuators. Fitting each channel to obtain sigma and position. Move DS far from beam core. Remove attenuators. Scan left beam halo @-400 V; BEAM OFF; move to the right; BEAM ON; Scan right beam halo @-400 V ~ 300 Scans, 5-7 min on average About 11 Gb of data for postprocessing. Data for Beam cores and beam halos need to be combined.

Data analysis. Postprocessing.

Role on the vertical beam halo of: Collimator Vacuum level (4.84e-7 Pa;   9.8e-7 Pa; 1.35e-6 Pa) Intensity And Additional characterization of our DS: charge collection by individual electrodes; step termination of charge collection; …

Vertical Beam halo scan. N ≈ 8e9 Red: 10x1 optics, σ= 1.46 mm Blue: 10x4 optics, σ=0.98 mm Determined the cut by the BDUMP aperture.

Investigated role of collimator on the beam halo cut Investigated role of collimator on the beam halo cut. 0.1mm of collimator displacement-> 0.5mm halo cut position. Limited range of collimator positions-> Observed effect only on the left side of halo (top side). Role of Collimator Cut from BDUMP aperture zoom Cuts from collimator

Displace the beam using Y shift on QD0FF from 300 mum to -1300 mum Cut from BDUMP aperture Cut from collimator

Vacuum level Vertical scan. N ≈ 8e9 (for better detection of halo) First complete scan of beam core and beam halo (red). Turned on ion pumps, vacuum level recovered quickly (5~10mins) to 4.4e-7. Second complete scan of beam core and beam halo (blue). Zoom of the beam core Rough estimation: Vacuum changed≈2 times and Halo changed ≈2 times Sigma CH1-CH4: 1.1989 1.0916 1.0924 1.2087 mm

Vacuum level Zoom of the beam core Red 4.84e-7 Pa Black  13.5e-7 Pa SigmaCH1-4: 1.19 1.09 1.09 1.24

Charge collection by different channels. N = 3e9 Small variation in Sigma 4 1 CH1 1 CH2 CH3 CH4 Plugged channel: 1 In air : 0

Problems/difficulties and future improvements Possibilities decrease pickup? After long DS operation at -400V the power supply started to provide large current… Fortunately with Keithley PS we can monitor it. The cause could be in the behavior of capacitors after long operation/irradiation… After 5 hours system is recovered. Vertical motor homing, brakes – controller software problem. Sometimes working/not working. Patch panel for the signal cables is hardly accessible. Difficult to insert/remove attenuators. 17/06 we removed it.

Temperature measurements Pt100 not plugged : PT100 : 89.13 / 41.97 / 27.53 degC PT100 : 89.13 / 59.06 / 27.53 degC PT100 : 89.13 / 76.38 / 27.51 degC Plugged: PT100 : 27.32 / 27.49 / 27.53 degC

Backup

Some improvements Added software communication with Keithley 2410 power supply. New algorithm for automatic determination of the best vertical range for the scope. Pdf report generator (waveforms, parameters…)

Horizontal scan. N = 2e9; Vacuum =7.87e-7 Beam core scan, beam steering, vertical alignment. Complete scan of beam core and beam halo: Sigmas CH1-CH4: 1.4396 1.3652 1.3614 1.4057 mm

Nonlinear regime of charge collection Predicted from the modelling step-like behavior in a waveform at the end of charge collection. Difficult to measure with 8-bit scope

1.1 What is diamond sensor? Diamond 1 MIP≈36 in 1 μm High Voltage Introduction to DS 1.1 What is diamond sensor? d=500μm 1 MIP≈36 in 1 μm High Voltage 400 V Reading side 0 V Diamond E = V/d