Subsystem Name: Front-End Boards part of WBS ??? Responsible Person: Dan Edmunds (MSU) Agreed By: Date: 15-March-2010 Document Version: 0.1 First Draft Inputs: [R] Up to 16 PMT signals on SHV connectors received over long RG-6 or RG-59 cables after passing through lightning arresters. [R] Up to 2 PMT High Voltage inputs on SHV connectors. The Front-End Boards may be setup so that either HV input will supply all 16 PMT channels or so that each HV input will supply just the 8 PMT channels closest to it. The total load on the High Voltage supply is: 19.9 Meg Ohm per PMT Base with 16 in parallel = 1.24 M 100.2 Meg Ohm per Chan HV Test Point 16 parallel = 6.26 M 100.1 Meg Ohm per HV Input Test Point 2 parallel = 50.05 M Gives 1.01 Meg Ohm total static High Voltage load per Front-End Board (about 1 mA per 1,000 Volts of PMT High Voltage). To this one must add the actual PMT tube current to get the load on the High Voltage supply. The 16 scaler mask control inputs from the backplane are not used in the HAWC application of the Front-End Boards. Outputs: [R] 16 TDC outputs - one from each PMT channel. Each TDC output is a time over threshold combination of the Front-End Board's low and high threshold comparators. The 16 TDC signals are differential ECL level, on 0.1" x 0.1" headers, pulled down by 270 Ohm resistors to -5.2 Volts, and expect 110 Ohm terminations. MC10105 driver chips are used. The TDC outputs drive the TDC module inputs. [R] 16 Solar TOT outputs - one from each PMT channel. Each Solar TOT output is asserted while the PMT input signal is over its low comparator threshold level. The 16 Solar TOT signals are differential ECL level, on 0.1" x 0.1" headers, pulled down by 680 Ohm resistors to -5.2 Volts, and expect 110 Ohm terminations. MC10101 driver chips are used for these outputs. Each of the 16 Solar TOT outputs must drive both a Scaler System input and a Digital Trigger System input. [R] 1 High Scaler output. This signal is a 20 nsec pulse anytime anyone of the 16 PMT inputs goes above its high comparator threshold level. This is a NIM level signal, driven by an MC10192, and is on a "LEMO" type connector. The single High Scaler output from each Front-End Board drives a single Scaler System channel input. None of the other outputs from the Front-End Boards are used in the HAWC experiment. Assumed Environment: [R] It is assumed that the same special crates and low voltage DC power supplies that were used for these Front-End Boards in the Milagro experiment will be used in the HAWC experiment. The infrastructure at the HAWC experiment site must provide the necessary racks, AC line power, and cooling to support the operation of the Front-End Board system. Each Analog F-E Board uses about 40 Watts of low voltage DC power and each Digital F-E Board uses about 22 Watts of low voltage DC power. The 900 PMT channels in HAWC will most likely require 60 Analog - Digital board pairs. Operation of these 60 board pairs will require about 3,720 Watts of low voltage DC power. Assuming about 65% efficiency this will require about 5,720 Watts of AC line power. To this must be added the power to operate the cooling fans for these cards. At this time I believe that all of the Front-End Board equipment is setup to operate for 120 VAC 60 Hz line power and has standard NEMA 5-15P or 5-20P power plugs. Control/Configuration/Download: [R] There are 3 trim pots on each Analog Front-End Board that must be checked and adjusted by hand. All boards are adjusted for the same test point reading of these trim pots. For "normal" operation at a certain time, some Front-End Boards may need to have certain PMT SHV connectors un-plugged, e.g. as documented in a log book. Functionality: [R] Provide High Voltage to the PMT bases either in groups of 8 or in groups of 16 bases with the same HV. [R] From the PMT signals provide a per channel time over threshold signal to the TDC system. [R] From the PMT signals provide a per channel time over low threshold signal to both the Digital Trigger System and the Scaler System. [R] From the PMT signals provide a NIM signal that is the "OR" of 20 nsec pulses - one from each channel every time it goes over its high comparator threshold. Performance Needed: [R] Per PMT channel provide a low threshold of about 1/4 PE and a high threshold of about 4 or 5 PEs. Required/Goals for VAMOS: [R] Provide the required Front-End Boards with their crate and low voltage DC power supplies to operate18 PMTs. Required/Goals for HAWC30: [R] Provide the required Front-End Boards with their crate and low voltage DC power supplies to operate 90 PMTs. Required/Goals for HAWC100: [R] Provide the required Front-End Boards with their crate and low voltage DC power supplies to operate 300 PMTs. Required/Goals for HAWC300: [R] Provide the required Front-End Boards with their crate and low voltage DC power supplies to operate 900 PMTs. Unit Testing Plans: As required, individual Front-End Boards will be repaired and/or modified either at LANL or at MSU. Integration Testing Plans: The bulk of the testing of the systems down stream of the Front-End Boards will be carried out using regular pulse generators making differential ECL or NIM test signals. Specialized tests, e.g. to confirm the correct signal levels and the correct termination, will be carried out by supplying a Front-End card pair (with if necessary a power supply appropriate for operating a single card pair) to the location where the specialized test will be conducted. Baseline Design: This is existing equipment that will be operated in HAWC in much the same way as it was used in the Milagro experiment. Equipment Budget: ?? Personnel Budget: ??