1. Status of NEWCHOD E.Guschin (INR), S.Kholodenko (IHEP), Yu.Kudenko (INR), I.Mannelli (Pisa), O.Mineev (INR), V.Obraztsov (IHEP), V.Semenov(IHEP), V.Sugonyaev (IHEP), R.Wanke (Mainz)… NA62 meeting, Ferrara, 3 Sept 2014

2. NEWCHOD geometry 144 individual tiles WLS + SiPM readout

3. Prototype scintillator counters Prototype:18 scintillator counters Dimensions:5 counters 30 mm (thickness) x 108 mm (width) x 268 mm (length) 9 counters 30 mm (thickness) x 108 mm (width) x 134 mm (length) +4 of special dimensions (around the beam + corner) Readout:16 Bicron WLS fibers  1 mm for big counters, 8 for small Photosensors: two pairs of 3x3 mm2 SensL SiPM per one big counter, two SiPM's per small counter

4. Scintillator counters Two rows will be mounted on one side of the Master plate, one row on the other

5. SensL MicroFC-30035-SMT SPECIFICATION from datasheet (at 21 o C): Sensitive area size : 3x3 mm 2 Number of p ixels : 4774 Pixel size : 35x35 µm 2 Gain : 3 x10 6 Operating voltage: V BR +2.5 V Dark count rate: 300 kHz (typ.) Crosstalk: 7% (typ.) Peak spectral sensitivity: 420 nm PDE at 520 nm: ~20% Overvoltage range: 1 - 5 V Typical overvoltage: 2.5 V Front side Back side Tested samples are in surface mounted package

6. SensL SiPM 3x3 mm 2 SiPMs

7. SensL signal from LED individual p.e. peaks are well separated

8. Crosstalk and dark rate Dark rate and level of crosstalk in SiPM are evaluated using a dark spectrum of a photosensor. Poisson distribution ratios allow us to calculate the parameters.

9. Photon detection efficiency (PDE) measurement LED generated short light pulses which are sent to a monochromator. Wavelength is selected to be 520 nm. Output light is splitted between two optical cables with ratio close to 1:1. The cable ends are mounted into ferrules with output apertures of 0.5 mm diameter. The reference photoreceiver is a calibrated Hamamatsu PMT R580-17 with green-extended photocathode. The accuracy of spectral calibration is estimated to be about 10%. The phototube measured the average number of photons from LED flashes. The setup is placed in a thermostat which keeps the preset temperature within 0.1 o C.

10. Photon detection efficiency PDE at 520 nm with subtracted crosstalk component. Error is determined mainly by calibration accuracy. Preliminary

11. Front-end Electronics (1) Master board, which houses 8 SiPM boards and 1 Amplifier board 16 channel Amplifier boards: Output 4-6 mV for 1 p.e. Power consumption 40 mW/channel SiPM boards (8 per Master board), house 2 Pairs of SiPM's SiPM board with pins, which position Black Head with 4*4 fibers; Guard plate, which prevents fibers from touching SiPM's

12. Front-end Electronics (2)

13. Status 18 counters are manufactured (with grooves), Tyvek envelopes in preparation. 64 SensL SiPM are bought and tested. 64 amplifier channels are manufactured and tested. Production of 4 mother boards, 32 SiPM boards, 32 Black heads in progress. 1mm Bicron fibers are already at CERN.

14. Plan Mechanics at CERN ?? Counters at CERN middle of September Electronics at CERN middle of October Assembly of mechanics, fibers preparation and gluing September-October Counters mounting September-October Transportation, Installation ?? Tests during NA62 run November