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LAV front-end board test Silvia Martellotti, Francesco Gonnella Photo Veto Working Group 3 September 2014 1 Silvia Martellotti - Laboratori Nazionali di Frascati Slide 2 LAV front-end 9U board 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati2 ToT mezzanine card (16 x) 2 channels and 2 threshold per board. Includes the circuits for: Clamp, Amplifier, Comparator & LVDS driver. ToT mezzanine card (16 x) 2 channels and 2 threshold per board. Includes the circuits for: Clamp, Amplifier, Comparator & LVDS driver. Sum mezzanine card (16 x) Sum 4 analog channels (8 x) Sum 16 analog channels (2 x) Connected to a 50W LEMO out Board controller (1x) Communicate using CAN or USB Allows setting and reading: Thresholds (set/read) Power connection (read) Board controller (1x) Communicate using CAN or USB Allows setting and reading: Thresholds (set/read) Power connection (read) Test pulse controller (1 x) Can set for each channel: Pulse height (set/read) Pulse width (set/read) Pulse rate (set/read) Test pulse controller (1 x) Can set for each channel: Pulse height (set/read) Pulse width (set/read) Pulse rate (set/read) 16ch IN Analog Analog 32ch OUT LVDS LVDS CANopen or USB IN OUT VME custom power Slide 3 LAV front-end electronics LAV electronics channel working principle 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati3 Split the input signal into two copies: 1 copy to comparator + 1 copy to analog sums Clamp the signal preserving its width, wide dynamical range is expected (MIP 70 MeV ~ 10 mV, high energy ~ 1V) Amplify the signal and compare with 2 thresholds Each threshold is independently adjustable up to 250 mV Produce an LVDS signal and send the signal to the digital read out board 16ch IN Analog Analog 32ch OUT LVDS LVDS CANopen IN OUT VME custom power High threshold Clamp Amp 6x Compare Lowthreshold LVDS LVDS Split to analog sum Charge reconstruction algorithm The actual dependence of Q on ToT can be obtained using a fit to the distribution of Q vs. ToT. This relation is in principle the same for all the LAV PMTs. The sensitivity of the method is reduced at high charge due to the exponential dependence of Q on ToT. Measure ToT vs. charge using QDC and TDC Measure ToT vs. charge using QDC and TDC only during calibration not during experiment Fit the function Q(ToT) (i.e. polynomial function) Fit the function Q(ToT) (i.e. polynomial function) During data taking, measure the time using a TDC only During data taking, measure the time using a TDC only Charge reconstruction in NA62 LAV To TDC Slide 4 Hardware setup Software flaw chart Test setup 3 September 20144 Repeat n times repeat n times TDC CAEN V1190B VME Bridge V1718 LinuxPC 32 ch GPIB programming x 2 x 16 32 ch VME Hardware layout Silvia Martellotti - Laboratori Nazionali di Frascati Slide 5 Test stand at CERN Silvia Martellotti - Laboratori Nazionali di Frascati5 The LAV front-end electronic test stand has been moved to CERN to allow in situ calibration and testing of the boards Test of all the 86 boards have been performed at CERN by F. Gonnella, V. Kozhuharov, S. Martellotti, M. Moulson The facility will be also used to characterize the boards we have provided to CHOD and CHANTI 3 September 2014 Slide 6 Board modification is done All modified boards have been delivered, mounted and tested. 5 boards have problems, 1 is still in Frascati 83/89 boards are ready 81/81 are installed we have only 2 fully working spares Investigations to fix problems on the remaining 5 spare is ongoing Silvia Martellotti - Laboratori Nazionali di Frascati6 3 September 2014 Thanks to Katelyn Fariss and Mia de los Reyes! Slide 7 Hysteresis ( hist ri:sis ) Time of threshold is measured with two different pulse setups: The mean values of the ToT distributions in the two setups are evaluated Hysteresis is evaluated with the following formula: Note that this strategy does not imply any knowledge on the threshold. 11 February 2014Francesco Gonnella - Laboratori Nazionali di Frascati7 threshold 5ns20ns5ns20ns Slide 8 Hysteresis 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati8 The hysteresis has been correctly modified Slide 9 Threshold offset 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati9 The new threshold offset is lower we gain some mV in sensitivity Slide 10 Threshold offset channel by channel 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati10 The offset is independent from the channel number Slide 11 Calibration slope vs channel 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati11 The amplification is dependent on the channel number, i.e. on the track length Slide 12 Calibration-line slope 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati12 The calibration-line slopes were not altered by the hysteresis modification Slide 13 Strange Time-over-Threshold 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati13 In few channels we have a peculiar ToT Slide 14 Time resolution 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati14 The time resolution is not effected from the hysteresis modification Slide 15 Time resolution vs channel 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati15 There is a clear dependence of the time resolution on the channel number and not on the mezzanine. This is under investigation. Slide 16 Efficiency drop 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati16 Before hysteresis modification: there were a drop in the efficiency curve for 18% of channel in leading only and 20% of channel in leading and training After hysteresis modification: the drop in all the efficiency curves disappeared! Slide 17 Conclusions 3 September 2014Silvia Martellotti - Laboratori Nazionali di Frascati17 Boards were modified, re assembled and tested in time We have 81/81 installed boards and 2 spares We will work to repair the 5 boards with some problems The performance is improved, not only the hysteresis: Efficiency drops disappeared We can now safely go down in threshold to 5 mV (even 4 if we smartly swap high and low threshold) Slide 18 Thank you for your attention 3 September 2014 18