Analog Card Outputs: - Low and High threshold Discriminator outputs these are per channel outputs and they are routed through the upper connector on the special backplane to the Digital card these are differential ECL signals one does not have access to these signals - ADC Output this is a per channel analog signal there is a 500 nsec delay line in each of these signals these are 100 Ohm differential analog signals one has access to these signals all 16 of these ADC Outputs are routed to a 34 pin header on the Analog Card - Solar Output this is a per channel analog signal these are 100 Ohm differential analog signals with no added delay one has access to these signals all 16 of these Solar Outputs are routed to a 34 pin header on the Analog Card - Analog Sum Output there is just one of these outputs per Analog Card this is actually a differential ECL digital signal if the instantaneous analog sum of all 16 PMT signals is above some threshold then this output signal is asserted the output of this comparator is a differential ECL signal which is routed through the upper connector of the special backplane to the Digital Card one does not have access to this signal Digital Card Outputs: - TDC Output this is a per channel digital differential ECL signal that uses the edges from the low and high threshold discriminators (plus some other logic) to make the fancy "4 edge" signal that controls the TDC for each channel these 16 signals are on a 34 pin header on the Digital Card the front panel label of this connector is "TDC" - Solar Physics Output this is a per channel digital differential ECL output signal these digital card output signals are based on the low threshold signals from the analog card in the documentation these signals are described as, "approximately 20 ns long for the Milagro boards (SN 1:20) and equal to the low threshold pulse length (time over low threshold) for the more recent boards (SN 21 and higher)" from the schematics I *think* it is more complicated than that on the card that we have at MSU (SN 65) the Solar Physics Output signal for a given channel is equal to the low threshold discriminator output for that channel with the rules enforced that this signal is at least 20 nsec long and that the falling edge of this Solar Physics signal must be at least 40 nsec after the falling edge of the high threshold discriminator signal for that channel these 16 Solar Physics Output signals, one per PMT channel, are on a 34 pin header on the Digital Card the front panel label of this connector is "Solar" do not confuse this with the "Solar Output" from the Analog Card - Low and High Multiplicity Outputs there is one copy of the high threshold multiplicity output and two copies of the low threshold multiplicity output signal per Digital Card these multiplicity output signals are analog signals to make the multiplicity signals the output signal from each discriminator (high or low) is stretched or clipped to 200 ns and when asserted it contributes 25 mV to the appropriate analog multiplicity output signal these are Lemo connectors on the Digital Card's front panel these Lemo connectors are labeled: "High", "Low", and "Trig. Solar" if you want it I can provide a more detailed description of these signals - Analog Sum this digital signal comes from the Analog card and is made into a Lemo NIM like digital output signal on the Digital card there is one of these outputs per Digital card this is just a NIM like Lemo version of the digital differential ECL "Analog Sum Output" signal from the Analog card the front panel label is "ASum" - Scaler Outputs these 6 signals are all digital NIM like Lemo outputs with one of each of the following per Digital Card: High Threshold Scaler Output the high threshold discriminator signals are stretched or clipped to 20 nsec the High Threshold Scaler Output is the "OR" of all 16 of these stretched or clipped high threshold discriminator outputs the front panel label is "High" Low Threshold Scaler Output aka Masked Scaler Output the low threshold discriminator signals are stretched or clipped to 20 nsec you then can then mask out any subset of these 16 stretched or clipped low threshold discriminator signals the Low Threshold Scaler Output (labeled "Mask" on the front panel) is the "OR" of all of these signals that were not masked out the "mask input" is a 16 bit single ended ECL signal that comes from the backplane in parallel to all Digital cards in the crate Scaler ORs Ch 0,2,8,10 Scaler ORs Ch 1,3,9,11 scaler ORs Ch 4,6,12,14 Scaler ORs Ch 5,7,13,15 to make these 4 signals the low threshold discriminator signals are stretched or clipped to 20 nsec and then OR'd as shown above with jumpers you can OR a combination of these 4 ORs the front panel labels of these LEMO connectors are: "A", "B", "C", and "D" - For the Digital card LEMO connector outputs there is some inconsistency between: the Digital Card documentation, the schematic, the reference designators and silkscreen labels on the pcb, and the front panel labels. It takes a while to dig through it all but eventually everything makes sense. ========================================================================= As far as I know the Milagro cards have the outputs described below. I assume that we are thinking of the "Solar Physics Output" from the Digital Card for use with triggering logic. Dan Analog Card Outputs: - Low and High threshold Discriminator outputs these are per channel outputs and they are routed through the upper connector on the special backplane to the Digital card i.e. one does not have access to these signals - ADC Output this is a per channel analog signal there is a 500 nsec delay line in this signal this is a 100 Ohm differential analog signal one has access to these signals because all 16 of these ADC Outputs are routed to a 34 pin header on the Analog Card - Solar Output this is a per channel analog signal it is a 100 Ohm differential analog signal with no added delay one has access to these signals because all 16 of these Solar Outputs are routed to a 34 pin header on the Analog Card - Analog Sum Output there is just one of these per Analog Card this is a differential digital signal if the analog sum of all 16 channels is above some threshold then this output signal is asserted the output of this comparator is a differential ECL signal which is routed through the upper connector of the special backplane to the Digital Card i.e. one does not have access to this signal Digital Card Outputs: - TDC Output this is a per channel digital differential ECL signal that uses the edges from the low and high threshold discriminators (plus some other logic) to make the signal that controls the TDC for each channel these 16 signals are on a 34 pin header on the Digital Card - Solar Physics Output this is a per channel digital differential ECL output signal these signals are described as, "approximately 20 ns long for the Milagro boards (SN 1:20) and equal to the low threshold pulse length for the more recent boards (SN 21 and higher)". from the schematics I think it is more complicated than that on the card that we have at MSU (SN 65) the Solar Physics Output signal for a given channel is equal to the low threshold discriminator output for that channel with the rules enforced that this signal is at least 20 nsec long and that the falling edge of this Solar Physics signal must be at least 40 nsec after the falling edge of the high threshold discriminator signal for the channel these 16 Solar Physics signals are on a 34 pin header on the Digital Card do not confuse this with the "Solar Output" from the Analog Card - Low and High Multiplicity Outputs there is one copy of the high threshold multiplicity output and two copies of the low threshold multiplicity output signal per Digital Card these multiplicity output signals are analog signals to make the multiplicity signals the output signal from each discriminator (high or low) is stretched or clipped to 200 ns and when asserted it contributes 25 mV to the appropriate analog multiplicity output signal these are Lemo connectors in the Digital Card's documentation these Lemo connectors are labeled: High Mult, Low Mult, and Solar Low - Analog Sum this digital signal comes from the Analog card this is a Lemo NIM like digital output signal there is one of these per Digital Card this is just a NIM like Lemo version of the digital differential ECL "Analog Sum Output" signal from the Analog Card - Scaler Outputs these 6 signals are all digital NIM like Lemo outputs with one of each of the following per Digital Card: High Threshold Scaler Output the high threshold discriminator signals are stretched or clipped to 20 nsec the High Threshold Scaler Output is the "OR" of all 16 of these stretched or clipped high threshold discriminator outputs Low Threshold Scaler Output aka Masked Scaler Output the low threshold discriminator signals are stretched or clipped to 20 nsec you then can then mask out any subset of these 16 stretched or clipped low threshold discriminator signals the Low Threshold Scaler Output is the "OR" of all of these signals that were not masked out for the High Threshold and Low Threshold Scaler output signals which Lemo is which ? the Digital Card documentation, the schematic, and the reference designators on the pcb do not match. Scaler ORs Ch 0,2,8,10 Scaler ORs Ch 1,3,9,11 scaler ORs Ch 4,6,12,14 Scaler ORs Ch 5,7,13,15 to make these 4 signals the low threshold discriminator signals are stretched or clipped to 20 nsec and then OR'd as shown above with jumpers you can OR a combination of these 4 ORs ========================================================================= ========================================================================= Outputs Labeled "Low", "High", and "Trig. Solar" ------------------------------------------------ - These are all analog output signals from the Digital Front-End card. - The generation of these signals starts with the Low and High threshold discriminators on the Analog Front-end card. - On the Digital Front-End card, individually for each of the 16 channels, these Low and High threshold discriminator outputs are stretched to 200 nsec long pulses. - In "real-time" an analog signal is formed whose value is N times 25 mV where N is the number of the 200 nsec long stretched discriminator output signals that are currently asserted. - Separate analog signals are formed for the Low threshold and for the High threshold discriminators. These are the "Low" and "High" analog output signals from the Digital Front-End card. - Notes: The documentation often calls these the Low and High Multiplicity LEMO outputs. The documentation does not say so but I'm pretty sure that the "Low" and "High" outputs swing negative, i.e. their signals are minus N x 25 mV. The 200 nsec long stretchers that are used to make these signals are used only for this purpose. I did not study it carefully but I do not think that these stretchers "update" if the discriminator output remains asserted for more than 200 nsec or if during the 200 nsec long stretcher window the discriminator output goes low and then high again. These "Low" and "High" analog outputs are the 3rd and 4th LEMO connectors down from the top of the card. There are two red LEDs near the top of the card labeled "L" and "H". These are illuminated when the "Low" and "High" analog signals indicate a value of approximately 9 or more respectively. I believe that the signals to these LEDs are further stretched so that the eye can see them even if they flash at a low rate. - The "Trig. Solar" analog output from the Digital Front-End card is not well described in the documentation but it is pretty clear from the schematic drawings how this signal is formed. The "Trig. Solar" output signals is derived from the "Low" output signal. I believe that the "Trig Solar" output also swings negative (just like the "Low" signal) but that its value is N x 50 mV i.e. it is twice as big as the "Low" signal. The "Trig. Solar" output signal is the top LEMO connector on the Digital card's front panel and it is labeled "Trig. Solar" on the front panel. On the Digital Front-End card printed circuit board the silkscreen reference designator for this LEMO connector is correct, i.e. "J252", but the functional label in "copper silkscreen" is not correct. In the drawing on page 16 of the Digital Card documentation this LEMO connector is labeled "Solar Low". The "Analog Sum" Output Labeled "ASum" -------------------------------------- - Note, despite its name this is a digital output signal. - In analog, all 16 PMT signals, after passing through the gain of 1 amplifiers in the High Threshold circuit, are summed together. This is a real analog sum, i.e. no discriminator threshold or fixed pulse length has been imposed. - This "real-time" analog sum of the 16 PMT signals is applied to a discriminator on the Analog Front-End card. . This Analog Sum Discriminator has its own Threshold adjustment trim pot on the Analog card. There are a total of 3 Threshold adjustment trim pots on the Analog card: TDC Low, TDC High, and Analog Sum. . The output from the Analog Sum Discriminator is basically a time over threshold type signal, i.e. it is not a fixed length pulse. . The Analog Sum Discriminator has some positive hysteresis to limit the amount of jitter in its output. . The differential ECL output from the Analog Sum Discriminator is sent to the Digital Front-End card. - The Analog Sum Discriminator output signal arrives on the upper mid-plane connector on the Digital Front-End card. - On the Digital Front-End card this signal is converted from differential ECL to NIM and is sent out the LEMO connector that is labeled, "ASum", on the Digital card's front panel. This is the 2nd from the top LEMO connector. - This output is a digital signal and it represents the time over threshold of the analog sum of the 16 "raw" PMT signals. - Notes: On the Digital Front-End card printed circuit board the silkscreen reference designator for this LEMO connector is correct, i.e. "J302", but the functional label in "copper silkscreen" is not correct. In the drawing on page 16 of the Digital Card documentation this LEMO connector is labeled "An. Sum". ========================================================================= Milagro PMT Base ---------------- - I believe that the DC resistance of a Milagro PMT Base is 19.81 Meg Ohms. - The Analog card itself has about 5 Meg to Gnd from all the voltage dividers to check the HV distribution. - So the total static load is about 20 Meg / 16 in parallel with 5 Meg. This equals about 1 Meg. - So the total static load of a full Analog card and 16 bases at 1 KV is about 1 mA.