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Radiation Units Radio Telescope. Geoffrey Lovelace 04/13/01. Source for units information: www.britannica.com Penguin Dictionary of Physics (1977). Radiation Units. Physical Units Roentgen (R) (oldest)

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radiation units radio telescope

Radiation UnitsRadio Telescope

Geoffrey Lovelace

04/13/01

radiation units

Source for units information:

www.britannica.com

Penguin Dictionary of Physics (1977).

Radiation Units
  • Physical Units
    • Roentgen (R) (oldest)
      • amount of radiation to produce 2.58*10-4 C / kg charge on ions of one sign in dry air s.t. freed electrons are all stationary.
        • All energy of radiation spent in freeing electrons
      • 1 C/kg = 3880 R
      • Used for X-rays below 4 MeV
radiation units3
Radiation Units
  • Physical Units
    • Becquerel
      • Amount of radioactive sample s.t. there is 1 atomic decay per second
      • Henri Becquerel: discovered radioactivity through experiments with uranium and other radioactive matter
    • Curie (Ci)
      • 3.7*1010 decays per second
      • Approx. activity of 1g radium
biological units
Biological Units
  • Gray (Gy)
      • Amount of radiation s.t. 1 kg of tissue absorbs 1 J of energy
  • Rad (rad)
      • Radiation Absorbed Dose
      • .01 Gy; amount of radiation s.t. 1 g of tissue absorbs 1 erg (10-7 J)
  • Relative Biological Effectiveness (RBE)
    • Radiation effectiveness varies with type
      • Particle radiation tends to damage tissue more than X-Rays or Gamma Rays
biological units5
Biological Units
  • Sievert (Sv)
    • Radiation in Gy multiplied by an RBE scaling factor
    • 1 Sv approx. 1 Gy for gamma rays (RBE=1)
    • Rolf Sievert: Swedish physicist , first professor of the Dept. of Medical Radiation Physics in Stockholm
biological units6
Biological Units
  • Rem (Radiation-Equivalent Man)
    • 1 Rem = 100 Sv=1 rad * QF
    • QF = Quality Factor (Acts as RBE)
    • QF = 1 for gamma, high energy beta
    • QF = 1.8 for low energy beta, QF=10 for neutrons
  • Smaller Units
    • Sv, rem can be too large
    • More common: mSv, mGy
works consulted
Works Consulted
  • http://www.britannica.com
  • Pitt, Valerie H., Ed. The Penguin Disctionary of Physics.
  • http://www.ki.se/onkpat/radfys/sievert/Sievert.html
telescope update
Telescope Update
  • Heterodyning Unit Completed
    • Punched holes for BNC voltage supplies, ground
      • For +12V, +15V, and +15-28V supplies
    • Soldered connecting wire for ground, voltage
    • Completed cable connection between oscillator and attenuator
      • SMA Male to SMA Male (Connector Type)
      • RG-58 coax cable (specify R=50 Ohm and thickness)
        • Cut as shown, attach connector, and crimp

RG-58 cut positions

Center connector

Insulator

Shield

Sheath

1/8” center only

1/4” shield+ins.+center

telescope update9
Telescope Update
  • First Test: Receiver, Heterodyning Unit
  • VCO correctly subtracts a variable frequency from the RF Signal
  • ~ 4 GHz RF from heterodyning unit detected
    • Source Uncertain
    • Metal case blocks this signal
  • Next Steps
    • Run Cable, Mount Receiver on Dish
    • Prepare computer software for FFT