VLPC system and Cosmic Ray test results

1. VLPC system and Cosmic Ray test results M. Ellis Daresbury Tracker Meeting 30th August 2005

3. Analog Front-End (AFE) Version 2 • New design of the readout electronics for VLPCs. • Step along the path to AFEII-t, which will add the ability to record TDC information for each hit. • Prototype AFEII boards have been used for the first time at D0 for work on the MICE tracker.

4. LVDS cables to VLSB module MICE tracker readout with VLPCs Waveguides Tracker AFEII boards VLPC cryostat

5. VLPC operating conditions • Temperature needs to be kept at 9.00 ± 0.02 K. • Cryostat/cryo-cooler combination controlled to hold cold-end at 6.8 K with heater on a feed-back loop. • VLPC cassettes have 8 heaters, controlled through the AFE board, that bring the temperature up to 9.0 K and maintain it. • Select appropriate bias voltage to optimise gain vs noise rate. Optimisation depends on expected data-taking rate. • Bias voltage is applied through the AFE board.

6. LVDS / VLSB • Low Voltage Differential Signaling (LVDS) is used to transfer the ADC data from an AFE board to a VME memory module. • The cable is connected to the AFE board through the AFE back-plane. • VME LVDS Serdes Buffer (VLSB) boards are VME devices containing memory and an LVDS interface. • When the AFE board passes through a data-acquisition cycle, the ADC values are sent to the corresponding VLSB board and can then be accessed over a VME/PCI interface (BIT3).

7. LVDS and VLSB LVDS cables 1553 Trigger/Timing VME/PCI VLSB modules

8. Initialisation • AFE boards need to be initialised before data-taking can begin. • This is achieved through the Mil-1553 interface. One 1553 can control all 4 boards on a MICE 2-cassette cryostat. • Initialisation includes: • FPGA power on, programming and testing • Trigger Pipeline (TRIP) chip programming • VLPC bias voltage and temperature control

9. Timing and Triggering • FPGAs require a 53 MHz clock. • AFE board has a number of operating modes: • Initialise • Acquire • Digitise • Readout • The clock and mode control used to be provided by a SaSEQ board, now provided by an Avnet board. • Avnet is able to control all 4 boards on a MICE cryostat at once and requires no software intervention to perform a trigger/acquire/digitise/readout cycle.

10. Avnet Board RS232 cable Connection to AFE Backplane External trigger

11. Readout Sequence • External trigger is generated (e.g. cosmic ray trigger scintillators). • Trigger is ANDed with a pattern that matches the tevatron bunch structure (needed for now, will be replaced in later use for MICE). • If trigger is accepted, signal is passed to Avnet board. • Avnet board causes the AFE boards to acquire, digitise and readout the data to the VLSB modules and then sets the AFE boards ready for the next trigger. • Data is retrieved from the VLSB modules over the VME/PCI interface to a Linux PC. • Timing is critical as the trigger signal to the Avnet board needs to arrive 7 “bunch crossings” after the light from the tracker arrives at the VLPCs.

12. Progress at FNAL • After a number of problems, have managed to operate the MICE cryostat with 4 AFEII boards. • Linux software written for MICE can now perform almost all of the initialisation sequence and was used for all data-taking. • Took data with an LED pulser attached to each VLPC cryostat in turn and then connected the tracker and collected a few thousand cosmic ray triggers! • Tracker system has been sent to Japan and is being setup there now...

13. G4MICE • Several new features have been implemented in preparation for the use of G4MICE in data-taking and analysis of the KEK data: • User applications • A few SciFi classes are now persistent • Interface to CERNLIB to make PAW histograms, etc • Code to decode raw data format • Code to handle calibration data • Code to handle “decoding” information (so far only for original three stations) • First version of visualisation • Existing reconstruction already works with real data classes.

14. Pedestal Widths Made with G4MICE

15. Calibrations – Cassettes 105 & 111 Made with G4MICE 10 PE 10 PE Cassette 111 Cassette 105 One channel from each cassette. Note 105 has a gain of ~20k and 111 has a gain of ~40k

16. High Gain Cassette – More Light Made with G4MICE

17. Calibration Results Made with G4MICE

18. First look at Cosmic data • Still require work on “cabling” information (i.e. which board/channel/MCM is connected to which Station/Plane/Fibre) • Cabling information only for original three stations at the moment. • Calibration applied to raw hits and normal pattern recognition applied up to the level of space points. • Still need CMM data on station positions before attempt at tracking can be made. • Need to construct a “dead channel” list to remove first 4 channels readout over LVDS. These channels are corrupted due to the very low data-taking rate. This is only an issue < 0.5 Hz!

19. Light Yield (no tracking cuts) Made with G4MICE

20. Doublet Clusters Made with G4MICE

21. Hit Distribution Made with G4MICE

22. Next Steps • Add code to cope with new station/waveguide decoding. • Make best guess of waveguide connections to new station (otherwise try all plausible options...) • Obtain and use CMM information for station alignment. • Improve calibration information. • Check higher-level reconstruction (points and tracks). • Finish executables and scripts for KEK test.