Amptek is proud to have supplied A121s for the JUNO mission to Jupiter. For more information about The Jovian Auroral Distributions Experiment (JADE) on the Juno Mission to Jupiter, including photographs of the Amptek A121 in place, click here.
Model A121 is a hybrid charge sensitive preamplifier-discriminator designed for use in fast pulse counting mode with microchannel plates, channels electron multipliers, low gain photomultiplier tubes, proportional counters and solid state detectors.
|Threshold||Model A121 has a nominal threshold referred to the input of 8 x 10-15 coulomb. This is equivalent to 5 x 104 electrons.|
|Threshold Stability vs. Temperature||0.5% per °C|
|Threshold Stability vs. Power Supply Variations (Vs)||-0.1% per mV|
|Unit-to-unit Threshold variation||±8%|
|Noise (typical)||15 x 10-16 coulombs RMS; 9,650 e– RMS; 19% of threshold|
|Noise Slope (typical)||1.8 x 10-17 coulombs RMS/pF|
Input Test: 4 mV through 2 pF
Q = CV = 0.008 pC = 5 x 104 electrons
|Analog Output (Pin 5) Sensitivity||120 mV (15 V/pC)|
|Analog Output Risetime||10 ns|
|Output (Pin 9)||5 V; 35 ns minimum|
|Dead Time||Fixed Dead Time. Minimum Dead Time 80 ns. See “Figure A. A121 typical dead time as a function of resistance” under Performance. From Pin 8 to +5 Volts DC.|
|Count rate||12 x 106 CPS periodic|
|Operating voltage||+5 to +7 VDC MAX. (25 mW)|
|Operating current (typical)||5 mA quiescent, plus 1.5 mA/MHz|
|Temperature||-55 to +85 ºC operational|
|Screening||Amptek High Reliability|
|Mean Time Between Failure (MTBF)||1.2/106 hrs @ +25 °C|
|Package||9 Pin SIP|
|Accessories||PC121 test board|
STEP INPUT THROUGH 2 pF TEST CAPACITOR
Top Trace: Input (Pin 1) 200 mV/div
Middle Trace: Analog Out (Pin 5) 1 V/div
Bottom Trace: Output (Pin 9) 5 V/div
Time Base: 50 ns/div
|Pin 2||Ground and Case|
|Pin 3||Threshold Adjust (5k ohms < RT: open for maximum sensitivity). See “Figure B. A121 input threshold vs. control voltage on Pin 3” in Performance.|
|Pin 4||Vs (+5 to +7 VDC MAX.)|
|Pin 5||Analog Monitor|
|Pin 6||Pulse Width Adjustment (RH RH = 0 For Minimum Pulse Width of 35 ns. See “Figure C. A121 typical output pulse width vs. resistance to ground from Pin 6” under Performance.|
|Pin 7||Ground and Case|
|Pin 8||Deadtime Adjustment (RL RL = 0 For Minimum Dead Time of 80 ns. See “Figure A. A121 typical dead time as a function of resistance. From Pin 8 to +5 Volts DC” in Performance.|
Trise: < 20 ns (negative-going edge)
Amplitude: 2 – 50 mV.
Charge transfer to the input is according to Q = Ct·V, where Q = total charge, Ct = value of test capacitor, and V = amplitude of voltage step. DO NOT connect the test pulser to the input directly or through a large capacitor (> 100 pF) as this can produce a large current in the input transistor and cause irreversible damage.
Amptek is proud to have supplied A121s for the JUNO mission to Jupiter, which entered into a polar orbit on July 4, 2016 to study Jupiter’s composition, gravity field, magnetic field, and polar magnetosphere. JUNO will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds.
Amptek’s A121s were used for the Jovian Auroral Distributions Experiment (JADE) on the Juno Mission to Jupiter. Following are photographs of the A121s in place: