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Radiation Units Radio Telescope

Radiation Units Radio Telescope

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Radiation Units Radio Telescope

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  1. Radiation UnitsRadio Telescope Geoffrey Lovelace 04/13/01

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. Works Consulted • http://www.britannica.com • Pitt, Valerie H., Ed. The Penguin Disctionary of Physics. • http://www.ki.se/onkpat/radfys/sievert/Sievert.html

  8. 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

  9. 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