Modification History of AMANDA TWR

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    Modification history for summer 03/04
    Modification history for summer 02/03

Modification History for summer 03/04:

       In 2003/2004, we had two primary objectives.  The first was to increase the data throughput so that the TWR system can trigger at much higher rates than in the previous year, and the second was to investigate possible hardware solutions to allow the formation of software triggers.  The system overview describes the system and changes to the TWR system in 2004.   The TWR04 is now reading at a trigger rate of 150 Hz ( and majority logic M=18), which is approximately double the rate (~90Hz) of the previous year.  Simulations show that detector sensitivity for physics objectives with low backgrounds can be doubled if the trigger rate is doubled.  Low background science objectives include the search for neutrinos from GRBs, the search for EHE diffuse neutrinos, and episodic emission from point sources. In essence, the AMANDA-II detector is 2x better than it was last year for these science goals.  The TWR readout is capable of 230 Hz of deadtimeless readout, but data traffic is prohibative at this time.  

A summary of the performance characteristics of TWR04 

Modification History for summer 02/03:

12/30/03 Removed AM-A, installed VME crates for TWR system. Installed TWR DL380 computer on network. Installed 576 lemo cables between TWR and SWAMPS and ORBs. Connected to fast out.

1/23/03 Installed crate 5 of TWR system. Re-arranged ~40 lemo cables to each channel. Removed cables from string 17, dead OMs, and optical channels that are now readout as electrical.

1/30/03 Solved problem with occasional crashing of TWR system Problem was in DSP code

2/05/03 Read-out of all channel implemented in MBS. (Prior to this only 4 VME crates of TWR channels were read-out, even though 5 VME crates were connected to channels.

2/07/03 Added two TWR modules to bring the number of channels to 576. Re-mapped cables to ~30 OMs to include Strings 1 and 2.

2/11/03 Discovered that many waveforms were exact duplicates. Error traced to logic of DSP code. New code developed by SIS and Karl Heinz on 2/11, implemented by W. Wagner, 2/11. New code was certified to work by W. Wagner on 2/11.

2/12/03 Discovered error which caused blank waveforms on approximately 30% of the valid waveforms. Error randomly affected all OMs. Problem traced to improperly set bit in TWR (this was a new bit that was not documented in the manual we have at pole. It was only discovered in conversations with SIS. The latest manual has this discription).

2/13/03 Adjusted thresholds of each channel so that P/V (using integrated charge) is visible, if possible. Prior to this the electrical thresholds were 180mV, much too high. The reason for the initial high values was to keep the data rates small. Adjusted delay in start time for each TWR module. Goal: set delay so trigger peak (the narrow line in LE distribution that is generated when the OM is the module that forms the M=24 trigger) in each OM is about 3us after the beginning of the waveform.

2/14/03 Put TWR system in final state for winter operation.

Steve Barwick
Last updated:  Feb 14, 2004