1. Managed by UT-Battelle for the Department of Energy Overview of SNS Beam Instrumentation for High-Power Operation of the Spallation Neutron Source Willem Blokland for Beam Instrumentation Group Spallation Neutron Source Oak Ridge National Laboratory S. Assadi C. Deibele Y. Liu J. Pogge S. Cousineau D. Jeon S. Zhukov S. Aleksandrov

2. 2Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Outline SNS Instrumentation Laser-based Instrumentation Transverse Profile Monitor Emittance Scanner Longitudinal Profile Monitor Electron Scanner Beam Position Monitor Bunch Shape Monitor Ridicules Beam Loss Monitor

3. 3Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 SNS Instrumentation SNS is built as a collaboration of five National Labs for $1.4 billion

4. 4Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 SNS Instrumentation SNS Beam Instrumentation Collaboration Setup Partner labs design and built instrumentation Reviews Local experts (to receive and help with final systems) Visits Issues Priorities Budgets Delays Result Main accelerator diagnostics are operational

5. 5Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 SNS Instrumentation Ion Source 2.5 MeV 1000 MeV 87 MeV CCL SRF,  = 0.61 SRF,  =0.81 186 MeV387 MeV DTL RFQ RTBT HEBT Injection Extraction RF Short Pulse Harp (RTBT) #1 Wire Scanners (Linac/RTBT/HEBT) #42 Video Screens (Injection/RTBT) # 5 Energy Degrader Faraday Cups (DTL/CCL) #6 Aperture (MEBT) #1 Beamstop (MEBT/CCL) #2 Bunch Shape Monitors (CCL/HEBT) #6 Allison & Harp Emittance Scanner (FE/MEBT) #3 Harp (RTBT) #1 Wire Scanners (Linac/RTBT/HEBT) #42 Video Screens (Injection/RTBT) # 5 Energy Degrader Faraday Cups (DTL/CCL) #6 Aperture (MEBT) #1 Beamstop (MEBT/CCL) #2 Bunch Shape Monitors (CCL/HEBT) #6 Allison & Harp Emittance Scanner (FE/MEBT) #3 Accumulation Target Pulse Train BPM #160 BLM #370 (30 IOCs) BCM (Diff BCM) #26 ChuMPS (MEBT) #1 Laserwire (SCL) #10 Electron Scanner (Ring) #2 Spark Detector (LEBT) #2 Residual Gas Analyzer (FE)#2 Laser Emittance (HEBT) Ion Profile Monitor (Ring) Ridicules (Idmp) Electron Cloud Detector BPM #160 BLM #370 (30 IOCs) BCM (Diff BCM) #26 ChuMPS (MEBT) #1 Laserwire (SCL) #10 Electron Scanner (Ring) #2 Spark Detector (LEBT) #2 Residual Gas Analyzer (FE)#2 Laser Emittance (HEBT) Ion Profile Monitor (Ring) Ridicules (Idmp) Electron Cloud Detector

6. 6Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Instrumentation in progress New instruments Unexpected issues - RGA Monitors, Spark Detectors Physics Requests (Non-interceptive/high intensity) - Electron Scanner - Ion Profile Monitor - Laser Emittance - Damper for e/p Operations (Safety) - Loss decay - Differential Current Monitor - 60 Hz Beam Accounting Existing instruments Reliability ­ became critical for ops User friendliness ­ non-experts to operate Additional capabilities - filtering - beam accounting Obsolescence - parts no longer available

7. 7Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Laser Striping Experiment SCL Laser Profile Monitors, 9-stations MEBT 3-D Laser Profile Monitor 1)MEBT Mode-lock laser initially in 1-D – 9/2004 2)SCL Nd:YAG 1064 nm Laser, 9-station – 9/2005 3)Laser Stripping test Nd:YAG, 3ed harmonic -- 8/2005 4)Working on making SCL Laser system turn-key -- to present 4M4H 1D Laser Emittance Laser-based Instrumentation S. Assadi HIB2008

8. 8Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 12345321712131415 250 m 227 m25 m160 m LR Laser room Laser wire station Cryomodule number Camera Mirror Power meter 32 LR Laserwire System Layout CCL 4 LW from 200 MeV 4 LW from 450 MeV 1 LW at 1 GeV Q-switched Nd:YAG laser  = 1.06  m f rep = 30 Hz, T w = 7 ns E p = 50 – 200 mJ Injection seeded Timing synchronized to SCL HEBT High pulse energy Small spot size Single wavelength Pointing stability Temporal stability S. Assadi HIB2008

9. 9Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Q-switched Nd:YAG laser 1064 nm 30 Hz 7 ns Up to 1.5 J Injection seeded Laserwire Transport Line S. Assadi HIB2008

10. 10Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Laserwire Progress Profiles have been measured at all 9 stations Repeatability Operational parameters have been investigated and optimized  Magnet strength  Laser versus ion beam position 12.9 12.4 11.9 11.4 10.9 10.4 9.9 9.4 8.9 8.4 7.9 7.4 Magnet Current (A) LW12 Pos B Laser beam shifts f Ion beam shifts Pos A Pos B S. Assadi/ Y. Liu

11. 11Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Laserwire Progress Software platform has been improved  Towards non-expert user Future Improve radiation hardness -> move drift compensation actuators to laser-room Improve stability with aperture restrictions Top-level Low-level

12. 12Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Advantages  Operable anytime even for production beam.  Can measure beam emittance at any part of beam pulse.  The same laser slit can be used for a wide range of beam energy such as beam energy ramp up to 1.3 GeV.  A laser slit can avoid scattering and thermal issues of conventional slits.  At most about 3~10% of 8 ns beam is stripped.  minimal radiation issues.  For resolution, a sufficient distance between slits and harps can be easily secured because H o beam is free from dipoles, quadrupoles and etc. Laser Emittance Scanner D. Yong/J. Pogge 20 mJ

13. 13Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Scintillator pickup  HEBT Bending dipole deflects H - beam and electrons  H o beam will travel free from the influence of dipoles, quads etc  Operable any time even for production beam HoHo H-H- D. Yong/J. Pogge/S. Menshov Laser Emittance Scanner Laser Slits

14. 14Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner: Principle  Look at the deflected projection of a tilted sheet of electrons due to the proton beam charge [1,2,3] –Neglect magnetic field (small displacement of projection) –Assume path of electrons is straight (they are almost straight) –Assume net electron energy change is zero (if symmetric).  or, take the derivative to get the profile [3] S X Y protons electrons [1] Paul D. Goldan “Collisionless Sheath---An Experimental Investigation”, Phys. Fluids 13, 1055 (1970), DOI:10.1063/1.1693008 [2] Tsyganov, E.; et al A., "Electron beam emittance monitor for the SSC," Particle Accelerator Conference, 1993., Proceedings of the 1993, vol., no., pp.2489-2491 vol.3, 17-20 May 1993 [3] Aleksandrov, et al "Feasibility Study of Using an Electron Beam for Profile Measurements in the SNS Accumulator Ring," Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the, vol., no., pp. 2586-2588, 16-20 May 2005 Imperfections estimated at 5-10%. W. Blokland/S. Cousineau/ Dmitriy Malyutin/Sasha Starostenko

15. 15Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Markers Electron Scanner Hardware Electron Scanner made by Budker Institute of Nuclear Physics: Dmitriy Malyutin, Sasha Starostenko, Sasha Tsyganov Vacuum vessel by SNS. 1)Build an electron gun (75kV) 2)Shoot a tilted line of electrons through the proton beam 3)Use a fluorescent screen and video camera to get the projected curve

16. 16Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner Hardware Electron gun Quadroples Corrector Deflector Camera Screen

17. 17Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner Software Simulation and image analysis

18. 18Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner Software Main control and profile reconstruction programs

19. 19Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner Images Images of the horizontal screen and fitting

20. 20Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner Data 3D plot of Turn 343 Ring BCM around Turn 343

21. 21Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner Data 3D plot of turns 10,20,30,50, and 55. 3D plot of turns 50,100,200,300,400, and 500.

22. 22Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Electron Scanner Progress We have produced lots of data profiles in the ring See within the turn Data Validation Shape of profiles matches RTBT Wire scanner measurements but width is off compared to model Vertical scan range too small for beam size Range from about 0.3uC (2e12p) to about 12uC We are learning the ins and outs of the device Operation: What settings make for good measurements, how to create a user-friendly interface Analysis: What technique works best (range, robustness) Light Sensitivity: Larger lens and more sensitive camera

23. 23Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Beam Position Monitors  RMS energy difference jitter is 0.35 MeV, extreme = + 1.3 MeV  Control of energy jitter is essential for reduced injection losses. 2 Degrees Measuring energy jitter Phase difference of 1000 pulses measured at 2 consecutive BPMs in SCL. Beam Current ~15 mA Pulse length = 20 µ sec C. Deibele

24. 24Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Beam Position Monitor Phase Phase measurements (solid) versus model (dots) See paper http://accelconf.web.cern.ch/AccelConf/p05/PAPERS/FPAT016.PDF Impedance matching to dipole mode C. Deibele

25. 25Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 http://it.sns.ornl.gov/asd/public/pdf/sns0004/sns0004.pdf Bunch Shape Monitor Alternative to BSM with RF deflector is a fast Faraday Cup (>20GHz, up to 7 MeV) 2 CCL, 2 HEBT BSM (Resolution ~10ps)

26. 26Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Bunch Shape Monitors An excellent beam instrument to diagnose: 1.Turn-on transient gives RF phase and amplitude variation during the pulse, beyond bandwidth of feedback 2. LLRF Feedforward algorithms Without Feed-forwardWith Feed-forward

27. 27Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 RIDICULES Uses: –Measure charge delivered to injection dump (Beam Accounting) –MPS in case of foil failure (faster than BLM) –Measure efficiency of injection into ring –Measure beam/charge to Linac Dump Circular electrode 1 mA Injection angle mismatch Ring Injection Dump I current Charge Unstripped Loss Efficiency System Desire to measure high dynamic range current in injection dump line. 40 mA to 1 uA, with 5% accuracy. Band-pass around RF frequency, amplify using logarithmic amplifiers, sample using dithering

28. 28Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 HIGH LOW Limiter Diplexer Data is dithered on the FPGA of the 2 ADCs into a single channel 2uA to 70 mA  90 dB dynamic range. http://it.sns.ornl.gov/asd/public/pdf/sns0179/sns0179.pdf RIDICULES

29. 29Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Beam Loss Monitors  Major MPS device –Fast MPS – abort the current beam pulse within 10 μS (analog integrator) –Slow MPS – keep average loss reasonable  Diagnostic device - machine tuning  Activation “planning”  Detectors –Ion chambers ~300+ –Neutron detectors ~30+ –Low level neutron detector 8 –PMTs ~10+ S. Zhukov

30. 30Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Beam Loss Monitors Additional Uses  Activation decaying  Activation buildup  Halo measurement with the help of WS shutdown begins Loss / WS conversion constant

31. 31Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Beam Loss Monitors Progress low energy beam (<20MeV) –IC not sensitive enough, ND sensitive, but hard to calibrate (no sufficient experimental data for reliable simulation). PMTs are supposed to help –Testing new system based on cRIO (includes FPGA) –Evaluating also PXI/VME and “smart-devices” Warm linac PMTs

32. 32Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Beam Loss Monitor Viewer Lossviewer2 (XAL application) BLM statistics web site

33. 33Managed by UT-Battelle for the Department of Energy ProjectX 11/21-22 2008 Summary We are improving existing instrumentation, have a new and exiting electron scanner to play with, and several new instruments in the pipe line.