E-beam scanner experience at FNAL 9th DITANET Topical Workshop on Non-Invasive Beam Size Measurement for High Brightness Proton and Heavy Ion Accelerators 15-18 April 2013 Randy Thurman-Keup… Déjà vu? Fermilab

9th DITANET Topical Workshop -- R. Thurman-Keup State of the Lab Fermilab currently involved in a mostly labwide shutdown Tevatron and associated antiproton facilities turned off 1.5 years ago Main Injector and Recycler are being modified to support combined operation where Recycler accumulates protons from the Booster Protons are transferred to the Main Injector Recycler accumulates more protons while simultaneously the Main Injector ramps the energy from 8 to 120 GeV and sends them to the Nova neutrino experiment in Minnesota This parallel running will reduce the cycle time by a factor of two Main Injector parameters 588 buckets; 500 filled; 1 abort gap 1-2 ns longitudinal sigma 3 mm horizontal x 1 mm vertical sigma (at the proposed location of e beam scanner) 1 x 1011 particles per bunch 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Main Injector Increasing beam power in MI/RR implies the need for non-invasive instrumentation Electron beam deflection technique is one choice (working implementation at SNS, see W. Blokland’s talk) Electron beam is deflected by electric and magnetic fields of the protons Deflection Angle Electron beam Proton beam out of page Deflection vs. Angle provides information about the proton beam transverse profile 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Techniques for Main Injector Various techniques for measuring deflection Fast scan through peak of bunch (see W. Blokland’s SNS talk) Requires fast deflector (< 1 ns sweep time) Slow scan, akin to flying wires (most likely solution in short time frame of Nova) Position the beam and record the maximum deflection as the beam passes by Leave the electron beam stationary Sweep the beam along the proton direction Obtain longitudinal distribution Collaborating with Wim Blokland at SNS who is doing simulations of the various techniques 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Electron Deflection Slow electron sweep Position the electron beam Record the deflection of a bunch Move the electron beam and repeat Plots courtesy of Wim Blokland 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Electron Deflection Simulation Step the electron beam through the proton beam and record maximum deflections Derivative of deflection vs. position is nominally beam profile Derivative Plots courtesy of Wim Blokland 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Alternative Deflection Scheme Electron Sweep Sweep the electron beam along the proton bunch Sweep duration coincides with the duration of the proton bunch Beam Sim. Transverse s = 3 mm Meas. Sim. Transverse s = 3.5 mm Beam Sim. Longitudinal s = 2 ns Meas. Sim. Longitudinal s = 2.3 ns 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Simulated Camera Image Camera frames are ~30 ms Main Injector cycle is ~1 s Need to step many times per frame to accumulate data fast enough for measurement Complicated to extract each step 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Electron Beam Device Ion Gauge Optical Breadboard ~ 60 cm x 150 cm Ion Pump 60 KeV Electron Gun Kimball Physics Beam Valve Electrostatic Deflector Elliptical Main Injector beampipe Ion Gauge Pneumatic Insertion Device with OTR Stainless Steel Mirror Optic components box Phosphor Screen P47, 400 nm, 60 ns decay(?) 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Optics Two optical paths: OTR screen and Phosphor screen with some shared elements SS Mirror Phosphor screen 45 Degree Mirror 45 Degree Mirror Lens on moving stage Lens on moving stage Filters and polarizers 45 Degree Mirror on moving stage Image Intensifier (Hamamatsu) CID Camera Megarad version Camera Objective 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Devices Kimball Physics up to 60 KeV (we will use up to 15 KeV) 6 mA, pulsed, 1 ms to DC LaB6 cathode, 100 mm spot size 15 cm long ‘circular’ plates ~2.5 cm diameter Electrostatic Deflector Thermionic Electron Gun Plates Solenoid and steering magnets Cathode 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Test Stand Optical Transition Radiation Screens Electron Gun Faraday Cup Lens / Digital Camera Imaging Systems 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Gun Tests Gun has internal solenoid Scanned beam through waist at first screen Scanned beam sizes from Ce:YAG screens (1 A beam) Scanned beam sizes from OTR screens (1 mA beam) 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Optical Transition Radiation Electron energy low Broad angular distribution Mirror should be 15 instead of 45 Light yield over the 2 ms electron pulse (E. Bravin, private communication) Initial beam images determined to be blackbody No polarization Intensity increased nonlinearly with duration Damage to stainless steel mirror observed 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Wire Tests Wire to simulate proton beam e Beam pulsed on for 40 ms Wire pulsed for 20 ms Half the time the beam is deflected 0V 50V 100V 150V 200V 250V 300V 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Test of Electrostatic Deflector ~120 V Deflecting Voltage vs. Deflector Length Deflector Pulse 80 ns 500 V Deflector Pulse 15 cm long plates ~190 V 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Electrostatic Deflector Test Longer sweep Bright part off screen Beam size not uniform Possibly due to poor pulse quality Short sweep Effect is similar proton bunch passing by 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Magnetic Fields in Tunnel Need to shield beamline First attempt will be mu metal Electron beam Quad busses 3500 A 5 gauss Bx 0 g By Dipole busses 9000 A 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

Electron Beam Profiler 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Optics Phosphor screen Image Intensifier 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup

9th DITANET Topical Workshop -- R. Thurman-Keup Conclusions Plan to install in Main Injector this shutdown But… Fermilab shutdown is Running out of time Running out of people Electron Beam Profiler is Behind schedule Not an officially supported project, i.e. no priority 16 April 2013 9th DITANET Topical Workshop -- R. Thurman-Keup