Resume of the experimental program up to date Hao Zhang

Previous Summary We successfully use the supersonic gas jet to monitor beam profile in ionization mode. We have a tool to measure the jet density which can be used to benchmark the simulation. Still make progress on the BIF mode.

Status up to date Proof-of-principle result of BIF mode Gas curtain distribution study Faraday cup installation and its result Lab move and resume of the experimental program

BIF monitor based on supersonic gas jet First &Second skimmers 180 mm & 400 mm Off centred nozzle hole Nozzle 30 mm 7.2 mm *1.8 mm 4.0 mm * 0.4 mm Third skimmers

Generation of supersonic gas jet

Vacuum consideration Number 1 2 3 4 6 Jet off (mbar) <5.0*10-4 2.1*10-6 9.7*10-8 1.8*10-8 5.36*10-10 Jet on (mbar) 5.5*10-3 6.9*10-5 4.8*10-6 2.3*10-8 1.21*10-9

Pump and Gauge Scroll Pump Turbo Pump Pirani Gauge Ion Gauge Number Brand Type Pumping Speed 1 ScrollVAC SC5D 5 m3/h 2 SD30D 30 m3/h 3 SD15D 15 m3/h 4 Number Brand Type Min pressure 1 Laybold Thermovac TTR91 DN16KF 5*10-4 mbar Number Brand Type Min pressure 2 Laybold Ionivac Sensor IE514 2*10-12 mbar 3 4 Pfeiffer PBR260 5*10-10 mbar 5 6 Brand Type Pumping Speed* 1 Pfeiffer TMU200MP 180 L/s 2 Leybold SL300 270 L/s 3 Hipace80 67 L/s 4 SL700 690 L/s 5 6 *based on N2 gas.

Details on the interaction chamber s (cross section) 9.2*10-19 cm2 I (electron current) ~10 uA n (gas jet density) 2.5*1010 cm-3 d (jet thickness) 2.8 mm Ω(acceptance solid angle) 4π·10-5 sr hpc(MCP photocathode efficiency) 0.2 hMCP(MCP detection efficiency) 0.5 T(Transmittance of optics) 0.65 Tf(Transmittance of band pass filter) 0.3 Blackened firstly by a Germany Company and then applied another layer of Graphite Ng = 0.08*Dt

Gas jet image from fluorescent 50 100 150 200 250 Shutter time: 8000s, MCP 1.0 V E-gun: 2.6A filament current 3.5keV energy X: 6.70, Y: 6.40, Focus: 5.55 Reflection of the hot cathode or E-beam on the tube joint ROI y x Residual gas image 141 mm Axis BIF IPM Xrms 1.96 mm 1.2 ± 0.2 mm Yrms 1.33 mm 0.4 ± 0.2 mm Compared to the Ionization mode 1pixel = 0.215 mm

Why so long integration time 1000s integration time is still good enough. Interaction cross section is low Photon transfer efficiency is not perfect Optics loss (lens and viewport) Bandpass filter loss MCP efficiency E-gun intensity is low Unknown (manual says 8uA when filament is 2.6A at E = 3.5keV)

Edge scan (large skimmer) Skimmer size 7.2×1.8 mm2 Oriental angle 45˚ Iion(X,Y)   Resolution: 1pixel = 0.2mm 4.5 mm 14.7 mm 15.2 mm 15.2 mm 19.2 mm 19.2 mm Differentiate the data in horizontal axis Jet size in interaction point is estimated as : 10.03 mm * 2.81 mm sjet = 0.99 mm

Beam enlarged by jet thickness View point View point ebeam ebeam Beam size mm sx (Gas jet) 0.5 ± 0.2 sy (Gas jet) Beam size mm sx (Gas jet) 0.4 ± 0.2 sy (Gas jet) 1.2 ± 0.2 sjet = 0.29 mm sjet = 0.99 mm

Faraday cup

Lab move Over one month’s waiting for the move 2 weeks for the electrician to install the power sockets IPAC Filament replacement of the old gun

After move experiments BIF test with the old E-gun after filament change. Previous steering location not work. Scanning the electron beam again? Still suffer from the long integration time. Change to new E-gun or New optics?

Summary We demonstrated BIF monitor based on supersonic gas jet. Further study of gas jet density under a larger skimmer continues to validate the measurement method and strengthen the understanding of the jet density distribution under different skimmer sizes. Faraday cup study showed the gun behave better than the manual for large filament current. Recover from lab move is still undergoing.