FToF wall TDR review D.VeretennIkov GSI 21.02.2017

Content Requirements and design MonteCarlo simulation Count rates  benchmark PID and T0 determination Test of prototype PMT check Plastic scintillator measurement Time resolution Summary Cost matrix Conclusion & Outlook

Overview of FToF detector 66 scintillation counters: 20 counters in the central part and 46 counters in the side parts (23 counters in each side part) FToF dedicated to measure the time of flight of forward particles emitted within the forward spectrometer acceptance with −5°< 𝜃 𝑦 <5° and −10°< 𝜃 𝑥 <10°

Forward TOF wall functions PID of forward emitted particles using time-of-flight information for low momentum hadrons: p/K separation at momenta < 4 GeV/c K/ separation at momenta < 3 GeV/c close to or below forward RICH threshold PID obtained using hits time correlations, without start counter Event start stamp reference time T0 provided a particle independently identified e.g. with FRICH or EMC(FSC) or Forward muon system Provide energy deposition information expected energy deposition range from 5 to 50 MeV

Technical requirements for the FTOF wall Time resolution better then 100 ps FToF wall positioned at 7.5 m downstream the target Sensitive area of the scintillation wall is 5.6 m (width) x 1.4 m (height) Thickness of the scintillator not more then 2.5 cm need by forward EMC Operate with counting rate about 1 MHz at PANDA high luminosity regime Dynamic range corresponds energy deposition from 5 to 50 MeV Operate at dipole fringe field of Bz < 80 G The opening in the wall for the vacuum beam pipe foreseen

FToF wall hadron PID 𝑚= 𝑝 𝑐 𝑡 2 𝑡 𝑐 2 −1 , 𝑡 𝑐 =𝐿/𝑐 σ = 50 ps 𝑚= 𝑝 𝑐 𝑡 2 𝑡 𝑐 2 −1 , 𝑡 𝑐 =𝐿/𝑐 σ = 50 ps p/K separation < 4.5 GeV/c K/ separation < 3 GeV/c 𝛿𝑚 𝑚 = 𝛿𝑝 𝑝 2 + 𝛾 4 𝜎 𝑇𝑂𝐹 𝑡 2 σ = 100 ps p/K separation < 3.5 GeV/c K/ separation < 2.5 GeV/c ToF resolution σTOF = 50 or 100 ps FS momentum resolution Δp/p = 0.01

FToF wall design Side part 23 slabs 10 cm width Central part The wall can be built of commercially available plastic scintillation slabs and fast photodetectors. Sensitive area is 560 cm (width) x 140 cm (height) x 2.5 (thick) Granularity : counting rate below 1 MHz at PANDA HL regime

Properties of plastic scintillators BC-400 BC-404 BC-408 BC-412 BC-416 Light Output, % anthracene 65 68 64 60 38 Rise Time, ns 0.9 0.7 1.0 - Decay Time, ns 2.4 1.8 2.1 3.3 4.0 Pulse Width FWHM, ns 2.7 2.2 2.5 4.2 5.3 Light Atten. Length, cm 160 140 210 Wavelength of max. emission, nm 428 408 425 434 Principal uses General purpose Fast counting Large area Large area Peak of light output at 425 nm well corresponds to most of fast PMTs

Attenuation length and rise time for BC408 GEANT4 calculations for BC408 scintillator 10x140x2.5 cm3 Light pulse detected at one end Beam of 500 MeV proton Depending on hit position BC408 Number of photons degrades by a factor of 3 while rise time is practically unchanged (about 1.3 ns) Time resolution is very sensitive to number of photons For long scintillators σ~ 1 𝑁 𝑝ℎ𝑜𝑡𝑜𝑛     𝑁 𝑝ℎ𝑜𝑡𝑜𝑛 > 10 4

Fast PMT properties R4998 R9800 R2083 R5505 R7761 R5924 PMT type   R4998 R9800 R2083 R5505 R7761 R5924 PMT type linear-focused fine-mesh Tube diameter 1” 2” 1.5” No.stages 10 8 15 19 Q.E. at peak 0.2 0.25 0.23 0.22 Gain (x106) 5.7 1.0 2.5 0.5 10.0 E.Transit Time, ns 11 16 5.6 7.5 9.5 Rise Time, ns 0.7 1.5 2.1 TTS, ns 0.16 0.27 0.37 0.35 0.44 HVmax, V 2500 1500 3500 2300 Time Transition Spread TTS: inherent PMT time uncertainty in response to a single photoelectron R4998 and R2083 easily protected with -metal against dipole fringe field of Bz ≈ 70 G

Supporting frame, mechanical components Supporting frame are made of duralumin HX4080E-8 profile Frame sitting on a rail and horizontal position of the wall can be fixed after alignment Frame is movable to the service position Expected total weight is about 800 kg

Due to cable length limitation need 4 TRB3 with 18 PADIWA 2 modules Front End Electronics. Connectivity TRB platform Trigger and Readout Board with on-board DAQ functionality fed with LVDS signal (cable < 200cm) TDC channels .…………………. 260 (8 ps) Max hit rate …………………..… 50 MHz Connectivity ……………………. 95 Mbytes PADIWA2 16 channel discriminator - fed with PMT analog signals, produces the LVDS signals both by the front and trailing part of analog signal and use Time Over Threshold TOT method of amplitude correction PADIWA3 AMPS contains ADC -> direct amplitude measurement Due to cable length limitation need 4 TRB3 with 18 PADIWA 2 modules

HV power supply Two HV patch panels, for left and right side Power supply, HV negative max 3500 V Worked out in PNPI for NUSTAR R3B 1000 PMT channels [L. Uvarov, “HVDS3200 the distributed high volt age system for Neuland spectrometer.”] Active dividers 200 μA current consumption (x 132 ch.) Produced in PNPI similar to [V. A. Kalinnikov, ” Low powered transistor divider for PMT. 2005. (in Russian)”]

MonteCarlo simulation. Count rates at PANDA HL regime Total rate 𝐩 elastic peak 𝐩 total All particle produced in vacuum pipe e+ e- produced in vacuum pipe from 0 →2 Pbeam, GeV  MHz K p MHZ 𝐩 MHz 2 0.39 0.002 0.012 1.07 5 0.6 0.008 0.038 0.95 15 0.96 0.047 0.032 0.82 !! Binning is 10 cm (width of slabs in the wall side part), including central part !!

Detection efficiency for different type of particles Number of detected particles for 107 interactions Detected by BToF Detected by DToF Detected by FToF N, x106 eff π- 4.08 0.36 0.14 0.01 2.59 0.23 π+ 5.03 0.44 0.03 0.002 2.07 0.18 K- 0.09 0.0004 0.001 0.1 0.26 K+ 0.25 0.003 0.046 0.12 𝐩 0.04 0.007 0.0002 3.24 0.62 p 3.19 0.61 0.012 0.35 0.07

Hit distributions for different type of particles

𝚲 detection Event selection criteria Pair of opposite charged hadron in events 𝑚( ℎ − )= 𝑚 𝑝 , 𝑚( ℎ + )= 𝑚 𝜋 𝑚( ℎ − )= 𝑚 𝑝 , 𝑚( ℎ + )= 𝑚 𝜋 , ToF criteria 𝛥 𝑡 𝑠𝑡𝑎𝑟𝑡 𝑝 𝜋 +  > 100 𝑝𝑠 Λ detected with high efficiency (~20%) at weak selection criteria  events also well detected At 106 interactions/s (normal luminosity mode) N Λ ≈4× 10 3 s-1 !!!

PID in event base simulation p = 5 GeV/c p.d.f for different particle types p = 0.5 GeV/c Track length and momentum from FTS ToF time from FToF Velocity 𝛽= 𝐿 𝑡 𝑇𝑜𝐹 Separate particle by  p.d.f for different particle types

T0 and PID determination 𝑡 1 𝑇𝑂𝐹 = 𝑡 0 + 𝐿 1 𝑐 𝛽 1 = 𝑡 0 + 𝐿 1 𝑐 𝑝 1 2 + 𝑚 1 2 𝑝 1 𝑡 2 𝑇𝑂𝐹 = 𝑡 0 + 𝐿 2 𝑐 𝛽 2 = 𝑡 0 + 𝐿 2 𝑐 𝑝 2 2 + 𝑚 2 2 𝑝 2 ……… 𝑡 𝑛 𝑇𝑂𝐹 = 𝑡 0 + 𝐿 𝑛 𝑐 𝛽 𝑛 = 𝑡 0 + 𝐿 𝑛 𝑐 𝑝 𝑛 2 + 𝑚 𝑛 2 𝑝 𝑛 n equations and n+1 unknown variables 𝑡 0 , 𝑚 1 , …, 𝑚 𝑛 𝑚 can be only 𝑚 𝑝 , 𝑚 𝐾 , 𝑚 𝜋 , 𝑚 𝜇 or 𝑚 𝑒 𝐿 and 𝑝 provided by tracking Loop over all possible ( 5 𝑛 ) combination and find right one TOF hits Need N ≥ 2 hits and can be done only offline, additionally provide T0 𝑡 𝑜 𝑒 𝑡 𝑜 𝜇 𝑡 𝑜 𝜋 𝑡 𝑜 𝐾 𝑡 𝑜 𝑝 time 1st hit, p = 5 GeV 2nd hit, p = 1.5 GeV 3rd hit, p = 0.5 GeV

No dedicated start counter. Hit multiplicity distributions Pbeam = 10 GeV Pbeam = 5 GeV Condition for ToF analysis (Nhits ≥ 2) at 10 GeV εBToF = 48%, εFToF = 38% and εBToF or FToF = 80%

T0 and PID algorithm with PandaROOT Events with only 3 FToF hits and beam momentum 15 GeV/c, ToF = 70 ps PID calculated using combinatory algorithm, colors correspond MC particle type PID quality (separation power) for all particle momentum ~20% for p/K separation ~10% for /K separation T0 resolution 90 ps

Prototyping. Test stand layout for PMT measurments 2 MeV energy deposition 2x104 photons Measured are TDC_1, TDC_0 Common start for all TDCs, QDC_1, QDC_0

Anode pulse rise time (ns) PMT characteristics PMT Photocathode diameter (mm) Anode pulse rise time (ns) Transition time (ns) TTS (ps) Gain / 106 Typical voltage (V) R4998 25 (1 inch) 0.7 10 160 5.7 2250 R9800 1.0 11 270 1.1 1300 R2083 51 (2 inch) 16 370 2.5 3000 R9779 1.8 20 250 0.5 1500 XP2020 1.6 28 ?? 30 2000

Test station results TDC1 gives raw t1 – t0 distributions Typical σTDC1 (raw) about 160 ps Offline amplitude correction 𝑇𝐷 𝐶 𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑 =𝑇𝐷 𝐶 𝑟𝑎𝑤 −𝐴 1 𝑄𝐷 𝐶 1 − 1 𝑄𝐷 𝐶 2 Corrections for start uncertainty, track walk and electronics 2𝜎 2 𝑅2083 =𝜎 2 𝑇𝐷 𝐶 1 𝑐𝑜𝑟𝑟 − 𝜎 𝑠 2 − 𝜎 𝑒𝑙 2 , 𝜎 𝑡𝑟𝑎𝑐𝑘 2 =15.8  𝑝𝑠, 𝜎 𝑒𝑙 2 =31.5 𝑝𝑠 PMT_1 σTDC_1 (ps) σPMT (ps) R4998 (4998/4998) 72. 44.4 R9800 (4998/9800) 86. 64.6 R2083 (2083/2083) 72.6 44.9 R9779 (2083/9779) 64 56.5 XP2020 (2.5, 2.36kV) 82 52.3 σTDC_1 after offline amplitude corrections σPMT after corrections for start uncertainty, track walk and electronics

Beam tests at 1 GeV PNPI SC 1 GeV proton beam and polyethylene target Scattered protons Count rate 103 to 106 /s cm2 Energy Ep=740 and 920MeV, σ(Ep) about 0.5% S3S4 scintillation slabs B408: Size (140)x(5/10)x(1.5/2.5) cm3 Energy deposition ≈ 5 MeV S1 and S2 size 2 x 2 x 2 cm3 Scintillation efficiency ~104 photons/MeV PMTs R4998, R2083, Electron187

Prototyping using proton beams PNPI 1 GeV synchrocyclotron 740 and 920 MeV protons selected with magnetic spectrometer COSY test beam in Juelich 2 GeV MIP protons Slab put horizontally in spectrometer focal plane at movable frame MWPCs provide hit position with σt = 1.8 mm precision 1 mm → 5.9 ps time uncertainty

Offline time resolution “Raw” time resolution can be substantially improved due to time-hit position and time-amplitude correlations Correction is done on event-by-event basis using correction function: 𝑡 𝑖𝑘 = 𝑡 𝑖𝑘 𝑟𝑎𝑤 − 𝑓 𝑐𝑜𝑟𝑟 𝑓 𝑐𝑜𝑟𝑟 = 𝑡 𝑖𝑘 𝑟𝑎𝑤 −𝐴𝑥−𝐵( 1 𝑄 𝑖 − 1 𝑄 𝑘 )−𝐶 tik , tikraw corrected and raw TDCi-TDCk distributions, x hit position, A,B,C constants to minimize functional: 𝑡 𝑖𝑘 2 − 𝑡 𝑖𝑘 2 = 1 𝑁 𝑛=1 𝑁 𝑡 𝑖𝑘,𝑛 2    − 1 𝑁 𝑛=1 𝑁 𝑡 𝑖𝑘,𝑛     2 TDC Hit position correlation hit position correction pulse amplitude correction TDC QDC (amplitude) correlation

Offline time resolution 920 MeV, position x = 60cm, Scintillator 2.5x5x140 cm3, R4998 Raw spectra After amplitude and hit position correction

Timing resolution results from 1 GeV PNPI SC 1 𝜎 𝑇𝑂𝐹 2 = 1 𝜎 𝑇𝐷𝐶3 2 + 1 𝜎 𝑇𝐷𝐶4 2 σTOF vs hit position

Scintillation slab dimensions (cm) Timing resolution σ (ps) Time resolution on beam tests Scintillation slab dimensions (cm) PMT Timing resolution σ (ps) Comment 140 × 10 × 2.5 Hamamatsu R2083 (both ends) 63 Recommended for a prototype for the FTOF wall. 140 × 5 × 2.5 Hamamatsu R4998 (both ends)  60 Recommended for a prototype for the FTOF wall 140 × 2.5 × 2.5 Hamamatsu R4998 43 a variant of a prototype with smaller scintillator width 140 × 5 × 1.5 Hamamatsu R4998 (both ends) 88 projected originally for the FTOF wall Electron PMT 187 (both ends) 78 magnetic field protected 1 × 1 × 1 Electron PMT 187, Hamamatsu R4998 49 “net” timing resolution of one PMT

Cost matrix 471k€ In Russian list of expression interest Item cost, € Plastic scintillator EJ200 140x10x2.5 cm3, 46+4(spare) units 33 800 Plastic scintillator EJ200 140x5x2.5 cm3, 20+5(spare) units 11 500 PMT Hamamatsu R2083 (2”), 92+8(spare) units 205 200 PMT Hamamatsu R4998 (1”), 40+10(spare) units 83 600 Light guides, optical cement 16 500 Supporting frame 15 000 Readout electronics, TRB-3, Padiwa-3 25 000 Active dividers (80€/unit) 10 500 HV power supply (90€/unit) 12 000 LV power supply 2 900 Laser calibration system 20 000 Mechanical components (PMT housing, μ-metal) 9 000 Transportation, custom taxation Equipment for tests and mass production Total 485 000 471k€ In Russian list of expression interest

Conclusion Size of wall is 5.6 m (width) x 1.4 m (height) x 2.5 cm (thick) Bicron BC408 plastic scintillator Hamamatsu PMT R4998 (1 inch) and R2083 (2 inch) MC simulation demonstrates important functions of FTOF wall: PID of forward emitted particles with momenta below 3 - 4 GeV determination of event start time stamp possibility to use Λ for detector calibration Maximum count rate in central part of FToF wall at L = 1032 cm-2 s-1 is below 3x106 s-1 . Background related to e+e- pairs production peaked at very low momenta is small. Measured timing resolution on prototype with 920 MeV protons (offline, after hit position and amplitude corrections) Only PMTs and front-end electronics  = 45 ps 140 cm x 10 cm x 2.5 cm BC408 scintillator + PMT + FEE  = 60 ps Without hit position information, timing resolution of 80 ps has been obtained.

Outlook and milestones TDR approved (M3) …………………………………………………………….… 12.2017 Working place for assembling and tests of scintillation counter modules organized ………………………………………………..… 12.2018 Funding established ..………………………………………………………..….. 03.2018 Contract is signed …………………………………………………………………. 12.2018 Tender completed ………… ………………………………........................ 12.2018 Procurement of necessary equipment for tests and calibrations (components not yet available) completed .……... 06.2018 Procurement materials for mass production (scintillators, PMTs, etc) completed …………………………………..…. 12.2018 Fabrication of mechanical items completed ……………................ 12.2019 Assembly, tests and calibration of scintillation modules ……….. 06.2020 Preassembly of the FToF wall …………………………………………………. 12.2020 Shipment to GSI …………………………………………………………………….. 06.2021 Integration in PANDA detector (M11) …………………………………….. 06.2022 Pre-tests, on beam tests (M12) …………....................................... 06.2023

Supporting slides

Risk assessments Risk item Probability Impact Mitigation measures Lack of manpower after 2016 not small Worsening detector tests and calibration. Extra time for mass production Search for additional funding. Search for PhD students Not sufficient financing for detector fabrication Not full scale detector (e.g. less FToF wall sensitive area) or worse timing resolution Search for additional funding like grants etc. Procurement of less expensive PMTs Timing resolution is worse than 100 ps Low Low PID quality Thorough tune and calibration using picosecond laser setup Lack of travel money high Problems with detector installation, maintenance and data taking Try to find additional financial support

Prototyping summary The time resolution of 60–65 ps was obtained for the scintillation counters recommended for prototypes for the FTOF wall. The time resolution of 50 ps was obtained for the slabs of 2.5 cm width. Practical application of such slabs however would result in increase of number of channels which may confront the detector cost limitation. The time resolution of 80 ps was obtained for the scintillation counter based on the slab of 2.5 cm width viewed with the Electron PMT 187. These mesh PMTs can operate in magnetic fields up to 0.5 T without deterioration of time resolution. Samples with slabs of 1.5 cm thickness originally projected for the FTOF wall showed essentially worse time resolution than those of 2.5 cm thickness. A precise measurement of the hit position seems crucial to get the timing resolution on the level of 60 ps. Without independent information on hit position, the timing resolution of 80 ps has been measured. . A satisfactory result was obtained for KETEK PM6660 samples at test station. A raw timing resoluton of σ = 71 ps (per a SiPM sample) was directly measured , and after corrections it was obtained σPM6660 = 66 ps. The measurements with large scintilltors has not yet been done. A very tentative test of radiation hardness of SiPMs has been made in PNPI using not powered S0931-50p SiPM (3x3 mm2) sample exposed to 1 GeV proton beam. It was found that the radiation dose equivalent to 0.45 x 1011 protons having passed through the active area of the sample is crucial for its operation capabilities.

Open questions MC simulation. Related to FSTT. - time dependent event reconstruction analysis Related to FSTT. - FS momentum resolution Δp/p must be 1% -vertical hit position uncertainty ? Δy=1 mm corresponds 5.3 ps (BC-408) expected at present design FSTT Δy=5-10 mm → up to Δ(tof) ≈ 60 ps -uncertainty in track reconstruction? ΔLtrack / Ltrack = 0.1% → Δ(tof) ≈ 30 ps FTOF wall position behind RICH. - RICH width is smaller than sensitive area of FTOF wall, deterioration of track information at FTOF wall side slabs FTOF wall width is 5.6 m while FSTT last station width is 3.9 m, thus side parts of FTOF wall are out of FSTT acceptance. reduce FTOF wall width ?? Hardware: - finalize TRB-3 readout tests - definitive decision on Hamamatsu PMs (type, housing, divider, price,.). - on-line laser calibration system (??) - HV-power supply: commercial or PNPI production HVDS3200 designed for Nustar R3B FAIR (neutron detector)

Time resolution without hit position correction

SiPM timing tests after corrections σ =103 ps Amplitude correction variant A S10931 after corrections σ =103 ps variant B KETEK 6660 after corrections σ =65 ps

PC Application of TRB-3 readout underway in PNPI generator mV Peak posit. σ ps 100 540 31.5 75 530 50 520 33. 40 34. 30 36. 25 510 Needs more expertise

Time and hit position measurements using TDC information only x (T41-T31)/2 σ431- (T41+T31)/2 σ431+ (T42-T32)/2 σ432- (T42+T32)/2 σ432+ cm ps 60 1504 99 11950 148,5 1503,5 100,5 11580 120,5 40 2770,5 74 11865 138,5 74,5 11510 102 20 3904 90,5 11975 145,5 11630 114 5025 76 11920 136,5 75,5 103,5 -20 6255 81,5 11940 150 82,5 115,5 -40 7460 84 11895 143,5 6890 85 11560 112,5 -60 8655 93,5 11945 11600 121 vBC408 = 1/59.12 = 0.17mm/ps speed of light in BC408 = 0.19 mm/ps hit position resolution 80ps x 0.17mm/ps = 13.6 mm

Cost estimation update FTOF wall Plastic scintillators B408 20u.140x5x2.5cm+46u.140x10x2.5cm 40 k€ PMTs 1” 760 € 40u. +5u.(spare) 42 PMTs, 2” 1270 € 92u.+20u.(spare) 155 FEE+DAQ 35 HV power supply 22 Monitoring/calibration system 25 Supporting structure , mechanical items 75 Test stand for mass production 35 Transportation, custom expenses 42 ……………………………………………………………………… 471 k€ From RRB February 2014 470 k€

LIGHT GUIDES FOR 1” AND 2” PMTs Plexiglas, Mylar wrapping, Magnetic field protected housing

Dipole TOF positioned inside the dipole magnet gap as planned for TDR Projected 2x10 scintillation slabs 80÷100x10x2.5cm readout from each end with Electron PMT 187 Diameter 30mm Photocathode 20mm Anode pulse rise time 1.4ns TTS ≈500ps Gain 5x105 W.m. emission 380nm ( 80% at 420nm) HV 1800v tested in magnetic field up to 0.5T Not sensitive to mag. F.(!) SiPMs(hamamatsu) S10931-50p, S10931-100p active area 3x3mm Pixels 3600 Gain 7.5x105 – 2.4x106 W.m. emission 440nm TTS 0.5-0.6ns(FWHM) Alternative solution SiPMs provided timing resolution better than 100ps radiation hardness??