Difference between revisions of "CDC Preamplifier Conclusion"
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| − | === | + | ===Results of Studies of the new ASIC Preamplifier=== |
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After discovering that the gas mixing system at CMU had malfunctioned, we switched | After discovering that the gas mixing system at CMU had malfunctioned, we switched | ||
to a premixed 90/10 Ar-CO2 mixture. Using the premixed gas, we were able to reproduce | to a premixed 90/10 Ar-CO2 mixture. Using the premixed gas, we were able to reproduce | ||
the observed behavior of old preamplifier. We then proceeded to compare the new preamplifier | the observed behavior of old preamplifier. We then proceeded to compare the new preamplifier | ||
with the old preamplifier. | with the old preamplifier. | ||
| − | # The gain of the [[PreAmp tests with premixed gas| new preamplifier]] is about a factor of | + | ====Conclusions of the Studies at CMU==== |
| − | two smaller than that of the old preamplifier. | + | # The gain of the [[PreAmp tests with premixed gas| new preamplifier]] is about a factor of two smaller than that of the old preamplifier. |
# We also observed that the output range of the old preamplifier was from 0V to 1V. E.g. we mapped 1V onto ~4000 channels in the FADC. The new preamplifier has an output range of 0V to 0.5V, with 0.5V being mapped onto ~4000channels in the FADC. This change was made to match the new 72-channel 125MHZ FADC. | # We also observed that the output range of the old preamplifier was from 0V to 1V. E.g. we mapped 1V onto ~4000 channels in the FADC. The new preamplifier has an output range of 0V to 0.5V, with 0.5V being mapped onto ~4000channels in the FADC. This change was made to match the new 72-channel 125MHZ FADC. | ||
| − | # | + | # In terms of the desire to increase the dynamic range of the CDC by a factor of two by decreasing the gain by a factor of two. This increase has been lost by the factor of two decrease in the output range of the new preamplifier. At the same operating point as before, the dynamic range of the new preamplifier/FADC-125 combination is the same as the old preamplifier. <font color=blue>We have not achieved the desired increase of dynamic range in the system</font>. |
| + | ====Alternative Approaches to Increasing Dynamic Range==== | ||
[[PreAmp tests with premixed 90/10 Ar/CO2 - software threshold]] | [[PreAmp tests with premixed 90/10 Ar/CO2 - software threshold]] | ||
Revision as of 15:57, 19 July 2010
Results of Studies of the new ASIC Preamplifier
After discovering that the gas mixing system at CMU had malfunctioned, we switched to a premixed 90/10 Ar-CO2 mixture. Using the premixed gas, we were able to reproduce the observed behavior of old preamplifier. We then proceeded to compare the new preamplifier with the old preamplifier.
Conclusions of the Studies at CMU
- The gain of the new preamplifier is about a factor of two smaller than that of the old preamplifier.
- We also observed that the output range of the old preamplifier was from 0V to 1V. E.g. we mapped 1V onto ~4000 channels in the FADC. The new preamplifier has an output range of 0V to 0.5V, with 0.5V being mapped onto ~4000channels in the FADC. This change was made to match the new 72-channel 125MHZ FADC.
- In terms of the desire to increase the dynamic range of the CDC by a factor of two by decreasing the gain by a factor of two. This increase has been lost by the factor of two decrease in the output range of the new preamplifier. At the same operating point as before, the dynamic range of the new preamplifier/FADC-125 combination is the same as the old preamplifier. We have not achieved the desired increase of dynamic range in the system.
Alternative Approaches to Increasing Dynamic Range
PreAmp tests with premixed 90/10 Ar/CO2 - software threshold
