Mossbauer Effect: Results for Natural Iron Absorber ( The Mossbauer Effect |experiments |Project Lab home ) ( |examples )

Apparatus Used and Experimental Parameters

• Radioactive Source: Co-57, 2 mCi on October 1, 1994 (half-life 271 days); Source no. 466-76, Isotope Products Laboratories, Burbank, Ca.
• Gas Proportional Counter: Reuters; gas 1 atm Kr-CO₂; operating voltage for this data, +1800 volts.
• FET-input preamp: TENNELEC Model TC-174, S/N 2690, Rev 4 (on loan from Prof. Barbara Neuhauser); NOTE: turn bias volage up or down by 500-volt stages, with a one-minute wait between changes.
• Shaping Amplifier: Canberra Model 816 (also supplies power supplies for the preamp). Input positive, Mode uni, coarse gain x32, fine gain x3.25.
• High-voltage bias supply: Canberra Model 3002, set to positive high-voltage (verify before connecting to preamp); fixed setting 1500 V, variable setting 300 V.
• Source Drive: A.S.A. Model K3 Mossbauer Linear Motor.
• Drive for Linear Motor: Tektronics FG503 Function Generator; Trig Out used to sync MCS, with period 0.21 sec (0.25 would have been safer),drive sinusoidal, amplitude 0.066 V pk-pk when connected to motor; the amplitude of the motion is small, perhaps 0.1-0.2 mm; more might be better.
• MCS function supplied by a Nucleus Series II Personal Computrer Analyzer, running on a Pentium I system under Windwos 98 in a DOS window.
  • The shaped output pulse goes to the main BNC input on the PCA-II interface card, accessible from the back of the computer.
  • The lower and upper limits, also on the PCA-II card and adjusted from the rear of the computer with a screw driver, are set when in PHA mode to accept just the 14.4-KeV nuclear gamma ray from the source.
  • The SCA output is looped to the MCS input, using the DB-9-to-BNC breakout adapter supplied with the PCA-II card.
  • The trigger signal goes to the SYNC input.
  • Settings (can also be read from the image above): Mode MCS, Gain 1024, display 1024, dwell 400 msec.