Radiation Units Radio Telescope

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Radiation UnitsRadio Telescope

• Geoffrey Lovelace
• 04/13/01

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Radiation Units
Source for units information www.britannica.com
Penguin Dictionary of Physics (1977).

• Physical Units
• Roentgen (R) (oldest)
• amount of radiation to produce 2.5810-4 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

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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)
• 3.71010 decays per second
• Approx. activity of 1g radium

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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

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Biological Units

• Sievert (Sv)
• Radiation in Gy multiplied by an RBE scaling
  factor
• 1 Sv approx. 1 Gy for gamma rays (RBE1)
• Rolf Sievert Swedish physicist , first
  professor of the Dept. of Medical Radiation
  Physics in Stockholm

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Biological Units

• Rem (Radiation-Equivalent Man)
• 1 Rem 100 Sv1 rad QF
• QF Quality Factor (Acts as RBE)
• QF 1 for gamma, high energy beta
• QF 1.8 for low energy beta, QF10 for neutrons
• Smaller Units
• Sv, rem can be too large
• More common mSv, mGy

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Works Consulted

• http//www.britannica.com
• Pitt, Valerie H., Ed. The Penguin Disctionary of
  Physics.
• http//www.ki.se/onkpat/radfys/sievert/Sievert.htm
  l

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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 R50 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 shieldins.center
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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