Status of pellet tracking — Multi-camera system developments

Status of pellet tracking - Multi-camera system developments. Readout electronics…. Mechanics (at UPTS) for additionally 4 cameras with lasers are ready. - Studies with pellets at UPTS Conditions as planned for PTR mode of pellet operation at PANDA. Position resolution, accuracy of extrapolated pellet position. DOF … effect of bad focus , pixel clustering. Efficiency of pellet detection. Rates etc… with different laser configurations. - Detailed system design for PANDA with optimized pellet detection levels. Position resolution and efficiency studies. Comparison of detection level configurations xzxz and zxxz. - Installation of the PTR system in the yoke recesses. Model studies. Allow increased pumping capacity, in particular at the dump. - Vacuum studies at WASA (COSY). Added PEG vacuum gauges in February …. Pellet tracking Panda CM GSI 2012 -12 -11 Hans Calén 1 (22) UPPSALA team Senior researchers: Ph. D student: Engineers: Hans Calén, Kjell Fransson, Pawel Marciniewski Andrzej Pyszniak Carl-Johan Fridén, Elin Hellbeck Project supported by JCHP-FFE, EC FP 7, SRC and FNP(eu-MPD)

UPTS performance August 2012 Pellet generation conditions: Nozzle 270 (F=12. 9 mm), TN=14. 1 K fdroplet ≈ 63 k. Hz, p. H 2 ≈ 400 mbar pdroplet_chamber ≈ 21 mbar (H 2 + He) vdroplet =22 m/s, ddroplet = 0. 34 mm pellet F=25 -30 micron (guess ) vpellet =77. 9 m/s, sv/vpellet = 0. 42% Windows center vert. dist. (mm) -76. 5 DC 0 VIC exit 271. 5 PTR gen Ppump_block ≈ 1. 2 e-3 mbar Above skimmer: PR ≈ 57 k. Hz FWHM=2. 1 mm FW ≈ 3. 7 mm Pellet tracking Panda CM GSI 2012 -12 -11 2 (22) 1513. 0 Skimmer F=2 mm 1860. 2 PTR up PTR chamber: PR ≈ 22. 5 k. Hz FW=2. 5 mm pdump ≈ 2. e-2 mbar 1939. 7 PTR low (2690 Cosy beam) (3500? HESR beam)

Pellet track reconstruction and extrapolation. Measure pellet positions at the dump floor. Select hits from pellets with “right” velocity and reconstruct tracks. Extrapolate the tracks to the VIC exit where the pellet beam is known (seen on monitor) to have a diameter of 50 -100 mm. Pellet tracking Panda CM GSI 2012 -12 -11 3 (22) Accuracy of extrapolated pellet position Pellet track x-distribution versus vertical position VIC exit 1. 5 m from skimmer Extrapolated track positions at VIC : s≈ 100 mm This corresponds to a position accuracy s ≈ 20 mm at the measurement levels (pixel size ↔ 37 mm). Positions measured just above skimmer and in PTR chamber. Lever arm = 427 mm. Pellet beam size ≈2 mm. Pixels (37 mm)

Pellet track reconstruction and extrapolation. Pellet beam a few mm out of camera focus …. Camera optics studies Pellet track x-distribution versus vertical position Pellet beam in camera focus VIC exit 1. 5 m from skimmer Must avoid/control out of focus effects … Pellet tracking Panda CM GSI 2012 -12 -11 4 (22) Extrapolated track positions at VIC : s≈ 100 mm Positions measured just above skimmer and in PTR chamber. Lever arm = 427 mm. Pellet beam size ≈2 mm. Pixels (37 mm)

Blurring due to limited DOF Camera optics studies DOF study with cam optics f=50 mm, bl. =1. 4, d(pelletstream – focalplane) ≈250 mm. Expect (geometrically) image size of 1 -2 pixels Pellet image size (pixels) d’ (mm) 8 Extrapolated position distribution s(pixels) at 1940 mm Out of field effects are severe outside +/- 2 mm of focus 7 6 s-a sigma-y at 1940 mm 5 Pellet tracking Panda CM GSI 2012 -12 -11 l-a sigma-y at 1940 mm a-a sigma-y at 1940 mm 4 3 2 5 (22) 8 9 10 11 12 13 14 d’ (mm) 15 16

Accuracy of extrapolated position for some different pixel-cluster sizes Camera optics studies 120531 10. 07 y 13. 42 x Cluster sizes s=small a=all l=large Cameras u=up (skimmer) d=down (ptr-lo dump) Class u-l Code sigma at 1940 mm 4 y x Extrapolated position distribution ss 1 2. 66 2. 51 s(pixels) 3. 5 sa 2 2. 79 2. 47 3 sl 3 2. 86 2. 42 as 4 2. 74 2. 59 2. 5 aa 5 3 2. 62 2 al 6 3. 16 2. 61 ls 7 2. 91 2. 61 1. 5 la 8 3. 47 2. 84 1 ll 9 3. 49 2. 85 sigma-y at 1940 mm sigma-x at 1940 mm 0. 5 0 0 1 2 3 4 5 6 Position resolution not too much influenced by pellet image size ! Pellet tracking Panda CM GSI 2012 -12 -11 6 (22) Increased image size may be due to: - electronics crosstalk - optics - off focus pellets - bigger pellets / pellet clusters - …. . 7 8 9 10

Illumination conditions. Cameras A Efficiency of pellet detection Different configurations with two laser beams give possibility to estimate the inefficiency due to limited illumination…. B E. g. with one laser in 135⁰ configuration it seems that one have an illumination inefficiency of 5 -20%. First detailed measurements to study this have been done …. Laser(s) … strong / many enough to give full detection possibility. Two laser beams seen (thanks to bouncing pellets) above the skimmer. Pellet tracking Panda CM GSI 2012 -12 -11 7 (22) Pellet beam crossing laser beams in the center of the tracking chamber.

PTR chamber at UPTS DN 150 CF FLANGE Height 220 mm Std CCD camera system Diameter 1000 mm Pellet tracking Panda CM GSI 2012 -12 -11 8 (22) CCD cameras are used for alignment of laser beams and for general monitoring in the PTR prototype section.

Illumination conditions. Camera A Laser(s) SNF lasers, 50 m. W, 1⁰ fan angle, 185 mm work distance Pellet tracking Panda CM GSI 2012 -12 -11 9 (22) Efficiency of pellet detection Different configurations with two laser beams give possibility to estimate the inefficiency due to limited illumination…. Measurement were done with two cams, one at each of the two levels of the PTR prototype chamber - Both lasers ON at both levels give similar Pellet. Rates. - As reference PRs from one level is used. - Comparison of rates with different combinations of two laser beams give possibility to estimate the (relative) inefficiency due to limited illumination…. With the laser beam at 135⁰ (transmission) we got <10 % inefficiency and at 45⁰ (reflexion) we got 5 -30%. The lasers are individuals …. . and this shows up most in reflexion mode since the pixel signal amplitudes are typically one third compared to transmission. - By comparing number of reconstructed tracks with the PRs one can get an estimate of the absolute efficiency. For each level we got an efficiency of 80 -85%. (From the camera cycle deadtime alone expects an inefficiency in the range 5 -15%).

Detailed system design with optimized pellet detection levels Lasers Version 0 tracking section: 4 levels (2 x, 2 z) , each with 2 lasers and 2 LS-cams. - Total height 400 mm. Radial size rmax = 500 mm. - Distance for velocity determination 60 – 260 mm. - Distance for direction determination 200 mm (…internally… if one use VIC exit: > 500 mm). Cameras Examples of some pellet tracking distributions at the interaction point. Time resolution (s ≈ 12 ms) Pellet tracking Panda CM GSI 2012 -12 -11 10 (22) Y-coord. resolution (s ≈ 0. 8 mm) Pellet Tracking Example study for Panda (A. Pyszniak) Generation point (VIC) at 3000 mm VIC position used for XZ tracking Measurement point 1 at 2300 mm (X) Measurement point 2 at 2240 mm (Z) Measurement point 3 at 2100 mm (X) Measurement point 4 at 2040 mm (Z) Interaction point at 0 mm Number of generated pellets: 100 k Generation frequency: 14, 20, 40 k. Hz Velocity mean: 70 m/s, sigma: 1% Stream divergence: ≈ 1 mrad Skimmer: 1 mm diam @ 2301 mm Pellet 25 μm, Pixel: 37 μm, Exp. Thr: 0. 05 Camera cycle/exposure: 4/4 μs Surv. prob. at gen. : 1 => Eff pel. rate at meas. points: » 14 k/s Half width of the search window: 2 vel. sigma Size of acc. beam: 5, 10 mm (sigma ≈ 1, 2 mm) Z-coord distribution Z-coord resolution (s ≈ 70 mm)

Position resolution at the interaction region. Detailed system design with optimized pellet detection levels Resolution in the vertical (Y) position, for different camera cycle times Camera cycle [ms] time 4/exp 4 time 2/exp 2 Y resolution [mm] 0. 85 0. 45 time resolution [ms] 12. 0 6. 5 Resolution in the horizontal (X and Z) position, for different measurement setup configurations …… with and without using the VIC exit position in the track reconstruction Lasers Cameras Configuration XZXZ with VIC ZXXZ with VIC Pellet tracking Panda CM GSI 2012 -12 -11 XZXZ w/o VIC ZXXZ w/o VIC X resolution [mm] 75 70 245 265 Z resolution [mm] 65 70 240 215 Level arms XZXZ -> 200 -200 mm, ZXXZ -> 140 -260 mm 11 (22) No difference with VIC +/- 10% difference w/o VIC

Detailed system design with optimized pellet detection levels Example of some pellet tracking performance numbers. Occupancy of acc. beam region (f=5 mm). Compare tracking prediction (trk) with mc reality (plt). Note: In this example a “trk” is based on full and correct information from all detection levels, a condition which is very strong…. . Cam cycle Plt rate Prb for no plt (ms) (k/s) when no trk t 4/e 4 5 0. 87 t 2/e 2 5 0. 88 t 4/e 4 14 0. 61 t 2/e 2 14 0. 63 Prb for 1 plt when 1 trk 0. 76 0. 82 0. 57 0. 62 Effect of detection inefficiency. Camera deadtime fraction of 20% in this example gives about 20% reduced tracking performance. Pellet tracking Panda CM GSI 2012 -12 -11 12 (22) Cam cycle Plt rate Prb for no plt (ms) (k/s) when no trk t 4/e 4 5 0. 87 t 6. 25/e 5 5 0. 82 t 4/e 4 14 0. 61 t 6. 25/e 5 14 0. 52 Prb for 1 plt when 1 trk 0. 76 0. 68 0. 57 0. 48 Correct match when 1 plt & 1 trk 0. 98 0. 99 0. 92 0. 96 Low pellet rate and high time resolution improves tracking performance (as expected). Correct match when 1 plt & 1 trk 0. 98 0. 95 0. 92 0. 83

Detailed system design with optimized pellet detection levels Status of design simulations (Andrzej Pyszniak, talk at SE FAIR meeting Nov 2012, see http: //www. physics. uu. se/en/np/panda/pub/) q q a procedure of pellet tracking has been implemented in the simulations q the MC is being used to determine predicted resolution and efficiency of pellet tracking for Panda q demonstrated transverse position resolution is adequate q vertical resolution with 3 -4 microsec cycle may be sufficient, but would be better with 2 microsec (cameras commercially available) q 13 (22) various aspects of pellets behavior and detection are simulated q Pellet tracking Panda CM GSI 2012 -12 -11 we have MC able to reproduce UPTS pellet experiments efficiencies according to TDR can be achieved i. e >70 % useful info with proper combination of PR (around 10 k/s) and beam size (5 -10 mm) q further optimization work in progress, both for equipment and procedures

Drawing (H. Orth May 2, 2012). Positions for target pipe valve flanges from TDR fig 9. 2 PTR flange at ≈100 mm below yoke outer surface Vertical slot for valve 114 mm Generator pit square 1. x 1. 2 m 2 0. 62 m deep Pit floor at r=1680 mm Pit ceiling at r=1790 mm Dump pit square 1. x 1. m 2 0. 51 m “deep” …. . but modification to house pump is expected Pellet tracking Panda CM GSI 2012 -12 -11 14 (22) Flange above valve at r=1794 mm Flange below valve at r=1879 mm Vertical slot for valve 89 mm PTR flange at ≈20 mm above yoke outer surface

PTR section conceptual design (2010) Height 400 mm DN 150 CF FLANGE Diameter 1000 mm Pellet tracking Panda CM GSI 2012 -12 -11 15 (22) Development of the procedure of installation in the PANDA iron yoke recesses and method of access to the PTR sections needs model tests.

Photos of PTR yoke-pit model. Fig. 25. Floor view from upstream. Poor space to connect PTR section above DN 160 valve. Yellow spacers have H=20 mm. Pellet tracking Panda CM GSI 2012 -12 -11 16 (22) 20120910 p. 3(8) Fig. 45. Side view from upstream. The bottom of the detection levels are shown by the corrugated cardboard sheets. On the lower two levels, foam plastic blocks illustrate the sizes of cams and lasers. The full height of a detection level is ≈ 60 mm.

Photos of PTR yoke-pit model. Fig. 53. View from downstream. The S-shaped pipe for pump makes it possible to have a pump in this quadrant. Pellet tracking Panda CM GSI 2012 -12 -11 17 (22) 20120910 p. 6(8) Fig. 54. View from downstream. A pipe inclined 30 degrees is possible in this quadrant but a pump (and valve) must be placed very high, sticking up above the pit.

From Alexander Täschner’s presentation at CM in Paris 2012 -09 -10 Pellet tracking Panda CM GSI 2012 -12 -11 18 (22) Place for 100 mm pipes and angle valves in two corners? (Need h ≈ 250 mm at a few positions. ) These pipes would be blinded during cluster source operation.

Fitting of the PTR system in the recesses in the iron yoke. General comment: The space needed for the actual PTR equipment is given in the TDR, i. e. for each section 0. 4 meter height and 0. 5 meter radially. This equipment fits in both the upper (1 x 1. 2 m 2) and lower (1 x 1 m 2) rectangular shaped “pits”. The PTR section will extend to ≈100 mm inside the yoke surface. (Then the pellet generator section can be placed at 2. 2 m distance from the accelerator beam (≈ 0. 85 m more distant than at WASA)). In addition, space for installation, adjustment and access for fine-tuning/service during operation is required. Some comments and conclusions from the model study. Pumps in the pit. A 30 degree tilted pump pipe (with valve) can be placed in one quadrant only. In such case the pump will extend outside the “pit”. S-shaped pump pipes can be put in 2 quadrants (3 if PTR section moved out ≈50 mm). The space for each pump can then be 200 x h 300 mm 3 (in quadrant corners). A 250 -300 l/s turbo would fit geometrically in this space. Installation of PTR section. Mechanics for cameras and lasers should be attached and aligned before installation in the pit. The PTR section should then be attached section to the target pipe. The access to the flange above the valve might be too difficult. In such case the space can be increased by moving out the PTR section a few cm. Access to PTR components during pellet operation. Pellet tracking Panda CM GSI 2012 -12 -11 19 (22) Fine-adjustment of cameras and lasers must be done with pellet beam. Then human access to the equipment is needed when the pellet generator and dump are in place (also for possibility to replace malfunctioning cams, lasers, LEDs …). This mainly concerns design and configuration of equipment placed just outside the pits. Camera electronics. Might be disturbed by pumps and magnetic field. The closest distances of camera to yoke iron and of camera to pump are 200 -250 mm in the model study…. Cameras need air cooling …. Some fans may do the job.

Fig. 9. 2 from Targets TDR (february 2012) Pellet tracking Panda CM GSI 2012 -12 -11 20 (22)

Pressures with pellets at WASA 14/8 -12 P(H 2)=625 mbar Generation f=85 k. Hz P(DC)= 18. 5 mbar Pellet counter=5000/s Target thickn=2. 5 e 15 at/cm 2 Pressures (mbar) PEG 3=1. 9 e-4 (2. 2 e-4) PEG 4=1. 5 e-4 (1. 4 e-5) PEGa 1=5. e-5(2. 2 e-5) PEG 5=1. 2 e-6(3. e-8) Backw. cone 1 Leybold 1500 cryo VIC length=70 mm F=1. -> 0. 7 mm VIC exit Distance (mm) 0 VIC exit 2 x 2000 l/s turbos (Hi. Pace 2300, TPH 2200) 2 TPH 2200 turbos 700 Skimmer (F 1 mm) 1345 Upper PTR section Pellet pipe (F 90 mm) (F 10 -5 mm) 2690 Cosy beam Be pipe (F 60 mm) PEGb 1=8. e-4(1. 5 e-6) Pellet tracking Panda CM GSI 2012 -12 -11 21 (22) PEG 6=2. 4 e-4(1. e-6) Dump 2 x 500 l/s turbos (TPH 510, TMH 521) 3692 Lower PTR section Forw. cone 2 Leybold 1500 cryos

Status December 2012 - - - 1 st prototype PTR system is in operation since March 2011 at UPTS : - Tracking chamber with two levels of pellet detection. - Two LS-cameras, now possible with three lasers each. Extension of the tracking system at UPTS to 6 LS-cameras: - Cameras & lasers purchased. Mechanics ready. - Development of a new r/o system (1 st iteration of el. nic boards). - LS camera (100 k. Hz model) performance well understood. . . … regular operation of 2 synchronized LS-cameras with 12 ms cycle. Required transverse position resolution has been demonstrated. Detection / illumination conditions … are being optimized. The first quantitative results from detailed detection efficiency studies show that it should be possible to reach close to 100%. Solution for good time ( y position) resolution and high camera efficiency exists. Pellet velocity spread sv /v <<1% should be possible to obtain. - Simulations for the detailed design of a system for PANDA in progress. Model studies for the installation of PTR system in yoke recesses. Vacuum measured at WASA, for use in PANDA design studies…. - - Pellet tracking Panda CM GSI 2012 -12 -11 Hans Calén 22 (22)

Target thickness fluctuations Number of pellets in accelerator beam vs time (during 5 ms) for pellet occurence frequencies, 15 & 150 k/s, and different pellet velocity spreads: MC results for pellet v=60 m/s and accelerator beam F=4 mm. (Pellet crossing duration ≈70 ms). f = 15 k/s sv /v=1% 23 (22) f = 15 k/s sv /v=0. 01% f = 150 k/s sv/v=1% Pellet tracking Panda CM GSI 2012 -12 -11 f = 15 k/s sv /v=0. 1% f = 150 k/s sv /v=0. 01%