A Brand new neutrino detector 「 SciBar 」 (2)

1. A Brand new neutrino detector「SciBar」(2) - Readout Electronics - Y. Takubo (Osaka) • Introduction • Readout electronics • Cosmic ray trigger modules • Conclusion

2. n SciBar detector • 2.5 x 1.3 x 300 cm3 scintillator strips • Extruded scintillator with WLS fiber readout • ~15000 channels • Light yield • 7~20p.e./MIP/cm (2 MeV) • Requirement for p/π separation • Dynamic range>10.6MIP(286p.e.) EM calorimeter Extruded scintillator (15t) 3m 3m Stopping p 1.7m Multi-anode PMT (64 ch.) Wave-length shifting fiber

3. Detector Components Timing distributor DAQ board Trigger board AMT 64ch MAPMT Front-end board

4. Requirement to readout electronics • Large number of channel (~15,000) • compact photo-detector and circuit • High sensitivity (MIP : 7 ~ 20 p.e./1strip) • Noise level < l p.e. (0.08 pC) • Large dynamic range (1 p.e. ~ 300 p.e.) for proton energy reconstruction • Fast trigger (Bunch identification) • VA/TA front-end electronics • DAQ board (VME) • AMT, Timing distributor

5. sample&hold preamp. 32ch VA serial output slow shaper CH1 TA (32ch OR) fast shaper discri. multiplexer CH2 CH32 Readout Electronics VATA is used for MAPMT for the first time. 1.2ms hold ∝ charge VATA Chip PMT signal (Energy information) (Timing information) Front-end board VA/TA chip A front-end board has two VATA chips.

6. DAQ board • DAQ board is custom module for SciBar readout. • Control of VA readout sequence • Setting of VA trigger threshold • VA serial output is digitized by FADC (dynamic range ~300 p.e.) • 8 front-end board (512 ch) are connected to one DAQ board. All channels (~15,000) are read by only 28 DAQ boards. VME bus Timing distributor 8 front-end boards(8×64ch） 16ch×2 TA signal

7. Timing Distributor Daughter board 16ch NIM I/O DAQ board 16×2ch LVDS/ECL Input FPGA • VME 6U module that distributes timing signals to DAQ boards through the bus. • 4ch NIM I/O on main board + 2 daughter boards Daughter board 16×2 ch LVDS/ECL Input 16ch NIM I/O • Flexible data processing is realized using FPGA.

8. AMT • Develop as Atlas Muon TDC(AMT) • VME 6U module • Multi-hit TDC • 64 channel in a module • 100 usec full scale • 0.78 nsec/count 64 TA signals All TA signals (448 ch) are read by 8 AMTs

9. Basic performance of VATA readout TA threshold curve Gain linearity 4000 600 3000 ADC cont 2000 Trigger efficiency (%) Noise hit 400 1000 20 40 0 Input charge (pC) 200 5% non-linearity < 24pC(300p.e.) 0 Gain distribution (all channels) 40 60 80 20 TA threshold (mV) TA threshold canbe set ~0.4 p.e. without noise hit. entries Gain: 80count / pC ~6count / p.e. < Pedestal( ~1.5count) 100 60 80 40 Gain (ADC count / pC)

10. Timing resolution Cosmic ray event is used to estimate timing resolution. Timing resolution is estimated by comparing timing of 2 channels. Correction of light propagation time in a fiber s = 4.03 nsec Timing resolution TQ correction s = 1.84 nsec = 4.03/√2 T(nsec) = 2.85 nsec Timing resolution = 1.84/√2 = 1.30 nsec 15 -10 0 10 nsec 0 10 -10 0 nsec -15 200 0 400 Q(ADC)

11. Track direction ID by TOF 3 super-layer penetration Track length = 50.5 cm T1 T3 Direction ID probability = 89.3% z1 z8 10 -10 0 SdT (nsec)

12. Achieved performance • 5 % non-linearity at 300p.e. • Noise level < 1 p.e. • sT= 1.3 nsec • p/p separation, momentum reconstruction • Uniform hit efficiency • Additional information for tracking • Neutrino event identification from neutron B.G.

13. Trigger scheme

14. Cosmic ray trigger modules Data taking cycle beam pedestal LED cosmic Time 2.2 sec Cosmic ray data is taken for the calibration in the off-spill. Trigger board is developed to take cosmic ray event effectively in the off-spill time

15. Logic for cosmic ray trigger Identification of hit track Make matching with two trigger signals 112 TA Trigger Board 7 DAQ Board Master trigger board 112 TA Trigger Board 7 DAQ Board Top & side view A half of the TA channels (224ch/448ch) are used for cosmic ray trigger.

16. Trigger Board Output : 1ch input : 128 ch (16×8) Output : 16 ch FPGA decide to make trigger signal. • VME 9U module • Front panel : input 128 (16×8) ch LVDS/ECL • Back plane : output 16ch LVDS/ECL • Using FPGA, trigger logic can be easily implemented for any combinations of 128 inputs.

17. Current status of cosmic ray event Hit distribution Current cosmic ray trigger takes all though going muons 250 Angle distribution Horizontal position(cm) 150 80 Zenith angle(degree) 0 0 80 160 Z(cm) ν -80 250 80 -80 0 Vertical position(cm) Azimuth angle (degree) 150 Horizontal line New trigger design is prepared to get horizontal events and uniform hit distribution. 0 80 160 Z(cm)

18. Trigger Design Requirement • Horizontally through-going muons are taken for calibration effectively. • Distribution of cosmic ray hits is uniform. • TA signals are trigger board inputs. Trigger design • Trigger is generated, based on the hit pattern identification. Preparing hit patterns, track pattern matching them is selected. • Track with less than 45 degree of zenith angle is taken.

19. Event display of cosmic ray event Side View Top View μ μ

20. Event display of stopping m event Top Side e e μ μ

21. Summary • SciBar detector uses VATA readout system. • It has 5 % non-linearity at 300p.e., and its noise level is less than 1 p.e..That satisfies required performance. • Trigger board is used for cosmic ray trigger, and upgrade trigger logic is prepared for effective data taking. • All readout system is working well.

22. Omake

23. Principle of VATA readout Pre-amp Fast-shaper TA Slow-shaper Hold_b 32ch VA serial output outm 1.2ms

24. Multi-anode PMT Top view • Hamamatsu H7546 type 64-channel PMT • 2 x 2 mm2 pixel • Bialkali photo-cathode • Compact • Low power : < 1000V, < 0.5mA • Gain : 6 x 105 • Cross talk : ~3% • Gain uniformity : ~20%(RMS) • Linearity : ~200 p.e.@ 6 x 105

25. Scintillator & WLS Fiber Scintillator 1.8 mmφ • Size : 1.3×2.5×300 cm3 • Peak of emission spectrum : 420 nm • TiO2 reflector (white) : 0.25 mm thick 300 cm • Kuraray • Y11(200)MS 1.5mmφ • Multi-clad • Attenuation length ~3.6m • Absorption peak ~430nm • Emission peak ~476nm 1.3 cm 2.5cm Wave-length Shifting Fiber Charged particle

26. Achieved Performance & Current Status of Cosmic ray trigger Achieved performance • Decision time is 100 nsec. • Single rate of one TA is about 100 Hz. • Trigger rate is about 100 Hz. • Data acquisition rate is about 20 Hz. Current Status We now use a trigger logic for the commissioning. We make “or” signals of every other layer, and make coincident with those of the top and side separately. We make “and” signal of the top and side.

27. Estimation of direction ID Track direction is identified by timing information. Top or Side view T1 T1 T2 T2 forward backward Tn SdT = Σ (T2- T1) Top&Side If n > 2, n n/2 SdT =Σ (-STi + STi ) Top&Side i=0 i=n/2+1 z1 z8 SdT > 0 : forward direction SdT < 0 : backward direction

28. 2 super-layer penetration Track length = 25.2 cm T1 T2 Cosmic ray Direction ID probability = 72.5% z1 z8 10 -10 0 SdT (nsec)

29. 3 super-layer penetration Track length = 50.5 cm T1 T3 Direction ID probability = 89.3% z1 z8 10 -10 0 SdT (nsec)

30. Hit distribution of cosmic ray event 250 250 Vertical position(cm) Horizontal position(cm) 150 150 0 0 80 160 80 160 Z(cm) Z(cm) ν ν