SNS Target Imaging and Related Developments

Transcription

1 SNS Target Imaging and Related Developments Tom Shea (ORNL) ESS Seminar Lund, Sweden January 28, 2011 T. J. Shea, T. McManamy, G. Bancke, W. Blokland, A. Brunson, M. Dayton, R. Fiorito, K. C. Goetz, J. Janney, M. Lance, C. Maxey, F. Montgomery, P. Rosenblad, S. Sampath, M. Simpson, T. Ally, Garcia, K. Hasse, Mitchell Multiple ORNL divisions, Stony Brook University, University of Maryland

2 Outline Brief history: SNS diagnostics deployment and commissioning Development of Target Imaging System (TIS) Imaging system performance with beam Related developments Summary 2 Managed by UT-Battelle

3 SNS Accelerator Complex Front-End: Produce a 1-msec long, chopped, H- beam 1 GeV LINAC Accumulator Ring: Compress 1 msec long pulse to 700 nsec Injection Collimator s RF Accumulator Ring Extraction 2.5 MeV 1000 MeV RTBT HEBT Front-End LINAC Liquid Hg Target Current! 945 ns Chopper system makes gaps mini-pulse Current! 1 ms macropulse 1ms 3 Managed by UT-Battelle

4 SNS Design Parameters Kinetic Energy 1.0 GeV Beam Power 1.4 MW Linac Beam Duty Factor 6% Modulator/RF Duty Factor Spec. 8% Peak Linac Current 38 ma Average Linac Current 1.6 ma Linac pulse length 1.0 msec Repetition Rate 60 Hz SRF Cavities 81 Ring Accumulation Turns 1060 Peak Ring Current 25 A Ring Bunch Intensity 1.5x Managed by UT-Battelle

5 The SNS Partnership During Construction Partner lab obligation completed: LBNL: Sept 2002* LANL: Sept 2004 JLAB: April 2005 BNL: April 2005 Beam Diagnostics partnership: LBNL, LANL, BNL, ORNL 5 Managed by UT-Battelle

6 Organization communication performance is correlated with technical performance* head *Allen, Goldhar, Baker, 1964 and on 6 Managed by UT-Battelle

7 Probability of Communication vs. distance 7 Managed by UT-Battelle T. Allen, Sloan WP , MIT, 1997

8 Commissioning ran in parallel with installation At LBNL Run #1: - RFQ (2.5 MeV), Jan 25th through Feb 2002 Run #2: - Front End (2.5 MeV), Apr 4 to May 31, 2002 At ORNL Run #3: - Front End again (2.5 MeV), Nov 5, 2002 to Jan 31, 2003 Run #4: - Front End, DTL tank 1, D-Plate (7.5 MeV), Aug 26 to Nov 17, 2003 Run #5: - Front End & DTL tank 1,2,3 (39 MeV) Spring 2004 Run #6 : - Front End, DTL, CCL modules 1,2,3 (158 MeV) Fall 2004 Run #7 : - Front End, DTL, CCL, SCL (1 GeV), Aug 2005 Run #8 : - Front End, DTL, CCL, SCL, Ring (1 GeV), Feb 2006 Run #9 : - Front End, DTL, CCL, SCL, Ring, Target (1 GeV), April 28, Managed by UT-Battelle

9 The Final Commissioning Run: Beam to Target 602 Diagnostic Devices MEBT 6 Position 2 Current 5 Wires 2 Thermal Neutron 1 Emittance Horizontal 1 Emittance Vertical 1 Fast Faraday Cup 1 Mode-locked Laser 1 Faraday/Beam Stop D-box video D-box emittance D-box beam stop D-box aperture Differential BCM DTL 10 Position 5 Wire 12 Loss 5 Faraday Cup 6 Current 6 Thermal and 12 PMT Neutron Differential BCM 9 Managed by UT-Battelle CCL/SCL Transition 2 Position 1 Wire 1 Loss 1 Current IDump 1 Position 1 Wire 1 Current 6 BLM CCL 10 Position 9 Wire 8 Neutron, 3 BSM, 2 Thermal 28 Loss 3 Bunch 1 Faraday Cup 1 Current 1 Dump SCL 32 Position 86 Loss 8 Laser Wire 7 PMT Neutron RING 44 Position 2 Ionization Profile 70 Loss 1 Current 5 Electron Det. 12 FBLM 2 Wire 1 Beam in Gap 2 Video 1 Tune HEBT 29 Position 11 Wire 46 BLM, 3 FBLM 4 Current EDump 1 Current 4 Loss 1 Wire RTBT 17 Position 36 Loss 4 Current 5 Wire 1 Harp 3 FBLM LDump 6 Loss 6 Position 1 Wire,1 BCM

10 Integrated Diagnostics for Beam on Target Prove We Met Project Execution Plan Criteria: 10^13 protons per pulse on target 5*10^-3 neutrons/proton*steradian from moderator Beam Current Monitor RTBT tunnel Layout of CD-4 Observation System Proton beam Target Target building Blokland Beam Current RTBT service building BCM interface Local log Mezzanine Target Viewscreen Neutron Time-of-flight* Moderator neutron detector Moderated neutrons Target Viewscreen* PC FO dist. Riedel PC FO dist FO dist. Neutron elec Iverson Local log Camera interface PC Shea Local log SM fiber - DeVan PC FO dist. MM fiber - Riedel Private UDP - Riedel ICS network - Williams EL/RTDL - Thompson Control room display - Purcell 10 Managed by UT-Battelle ` remote log *temporary

11 Temporary Target Viewscreen Uncooled Chromium- doped alumina viewscreen Redundant optical fiber bundles and cameras in service bay Removed before power exceeded 20 kw Viewcreen on target nose Camera system on target cart 11 Managed by UT-Battelle

12 12 Managed by UT-Battelle

13 Permanent Target Imaging System (TIS) Rad hard, 11 meter fiber optic cable turning mirror and focusing elements 25 mm ID viewport luminescent coating beam Parabolic mirror 2.2 meters Target 13 Managed by UT-Battelle

14 Candidate Photon Sources Source Screen* (Cr:Al2O3) 2*10 +2 Coating (Cr:Al2O3) 2*10 +1 Optical Transition Radiation 3*10-4 Helium scintillation (10 mm) 3*10-3 Thermal Incandescence Photon yield (photons/ proton/steradian) (nonlinear) * Ruby screen used during low power commissioning 14 Managed by UT-Battelle Fiorito et al, UMD

15 Luminescent Coating Development 800 MeV beam test at LANL Structure of powder before spraying Electron backscatter image of coating 1 GeV test at SNS linac: 0.25 mm coating produced 1/17 intensity of 1 mm Ruby plate 15 Managed by UT-Battelle Kenik, Sampath, Blokland T

16 Luminescence intensity increases with the amount of alpha alumina (corundum) intensity 16 Managed by UT-Battelle F. Montgomery

17 Automated Target Coating Stony Brook University 17 Managed by UT-Battelle

18 Coating Pattern Target 2 Pre-reacted Ruby Targets 3 and 4!"#$%&'()'!"#$"%&!'#!"#$%&'*)'$"%&!'# ()*+,+-.#/"*#0,/-#"/# 1%*'-1#!"#$%&'+)',!#(-*+,$-#!"2#3#("#/%*#("#'"".# Alumina Alumina/Chromia blend Find target center to +/-1mm 18 Managed by UT-Battelle

19 Component Layout from RTBT BCM 19 Managed by UT-Battelle

20 Optics: Some Design Challenges Only a small (<1 dia) viewing tube is possible: low light collection For a 1.5 MW year window life, the dose in Si at 1 m above beam (window location and transition to fiber) is about 1x10 8 rad An optical element must also be located at the in He near the hottest point 20 Managed by UT-Battelle Dose calculations: Ferguson, et. al.

21 Optics on Proton Beam Window Turning mirror, lens, beginning of fiber bundle Shielding Window 1: no optics Window 2: optics survived for life of window Window 3: improved optics installed and ready for beam in Feb mm view tube convex mirror 21 Managed by UT-Battelle proton beam flight tube View of mock target nose as seen from flight tube

22 Improved Optics Window 2 3 fused silica refractive elements Wide field of view Image onto bundle of 10,000 fibers 700 nm center, 80 nm FWHM Window 3 2 fused silica refractive and 1 fused silica diffractive element Tighter field of view Image onto bundle of 20,000 fibers 22 Managed by UT-Battelle

23 Predicting Beam-on-Target Parameters with RTBT Wizard application halo thermocouples BPMs Harp, BPM 4 wire scanner emittance station M. Plum, S. Cousineau 23 Managed by UT-Battelle

24 First Beam Images 24 Managed by UT-Battelle

25 Beam Study of 5 Extreme Cases (3/22/10) 1 2 Size, peak densities and center locations compared between Wizard predictions and TIS measurements Super-Gaussian fits cross-checked with 3 codes: generally agree well with each other 5 3 We believe beam can be centered on target geometric center to a few mm 25 Managed by UT-Battelle 4 Trends all agree well, but TIS generally shows a lower peak density and larger beam size than Wizard (by up to 40%!)

26 Uniformity: scan with small beam spot 26 Managed by UT-Battelle

27 Uniformity Early in target life Later in target life Horizontal Vertical Managed by UT-Battelle

28 Calculated Radiation Damage to Coating >85% due to neutrons DPA in the alumina spray (dpa/sns yr/mw) X (cm) Managed by UT-Battelle Y (cm)

29 Target 2 coating lasted full life of target Efficiency Plot- Sep 09 Jun 2010 Target 3 is similar Increase due to gas impurities from seal leak Shutter delay to eliminate gas flash with gas scintillation 90% intensity drop after 100 MW-hours (~0.1 dpa, point at which suspected neutron-induced F-center production saturates); then slow intensity reduction to 3200 MW-hours 29 Managed by UT-Battelle kw-hrs shutter delayed to gate out light from Helium

30 Emission Spectrum vs. Integrated Beam Power 1562 MWHr 808 MWHr 196 MWHr 125 MWHr 68 MWHr 16 MWHr 6 MWHr

31 Identify Emission Lines B5#7779>!;# 4-5#7?<9<!;# 4-5#<<79=!;# 4-5#6789:!;# 4-5#>?89<!;# 4-5#<><9?!;# 4-5#7A=98!;# 4-5#>=79<!;# B5#=669<!;#

32 Line intensity vs. MW-hours R-line Intensity vs. MW Hours on Target Suspected Oxygen Line Intensities vs. MW Hours on Target 32 Managed by UT-Battelle

33 Expect Emissions from F-centers Where are they? F 2 : 466nm F 2 : 550nm PL spectra of a sapphire crystal before and after neutron irradiation: î! 10^ 19cm 2 = (1) 0, (2) (3) (4) 0.01 (5) 0.05 (6) 0.1 (7) 0.5 (8) 1 (9) 5 Abdukadyrova, 2007 F+ 2 : 380nm F+ 2 : 756nm F: 420nm F + : 504 and 517nm

34 Images vs. Wavelength

35 Luminescence Lifetime at 560 nm Filter centered at 560 nm" Typical image, 200 ns shutter Photon yield vs. time Vertical log scale microsecond Managed by UT-Battelle

36 Luminescence Lifetime at 692 nm Filter centered at 692 nm (at R-lines) " typical images, 800 ns shutter, at beam arrival time (left), and 6 microseconds later (right) Photon yield vs. time Vertical log scale 4566'-2%786"92%:)' C*"%.D%!.#,;%',!'#(E"2(# 0,/-&;-(#1E%1#.-F-!.#"!#D-%;# *-F-&&"!#*%1-# 10 1 millisecond Managed by UT-Battelle

37 Reflections, Focus Issues Vertical slices of pencil beam 37 Managed by UT-Battelle

38 Effect of Beam Position on Neutron Production pencil beam 38 Managed by UT-Battelle Iverson

39 Audio from full Beam Pulse at 1 Hz Audio File 39 Managed by UT-Battelle

40 Amplitude of Audio Signal vs. Vertical Beam Position Channel A Channel C 5 mm Channels A and C are from upper moderator. Channel B is from lower moderator. Channel B 40 Managed by UT-Battelle

41 Upgrades, Applications, Related R&D Planned 41 Managed by UT-Battelle Improvements already deployed for February re-start Accelerator physics studies to further assess TIS accuracy Proposal for injection dump imaging system Development of neutron imaging devices Deferred due to budget constraints: Low noise camera and 60 Hz acquisition Instrumenting of Window 4 with multiple optical paths Alternate luminescent coatings Irradiation testing of coating samples Beam tests at SNS, LANL and/or other facility Optical modeling and bench measurements Online measurement of core vessel emission spectrum Development of proton beam window imaging concept Audio integration

42 Summary SNS partnership achieved successful commissioning runs and now, successful operations Target imaging system successfully deployed, but absolute density measurements need work Plenty of interesting science and additional applications to pursue 42 Managed by UT-Battelle