The roentgen (R, also röntgen) is a unit of measurement for exposure

  • Thread starter Thread starter RADboy
  • Start date Start date
  • Tags Tags
    Measurement Unit
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
Sign up Log in
1 reply · 4K views
RADboy
Messages
13
Reaction score
0
The roentgen (R, also röntgen) is a unit of measurement for exposure to ionizing radiation (such as X-ray and gamma rays), and is named after the German physicist Wilhelm Röntgen. Adopted in 1928[1], 1 R is the amount of radiation required to liberate positive and negative charges of one electrostatic unit of charge (esu or StatCoulomb) in one cubic centimeter of dry air at standard temperature and pressure (STP).


"1 R is the amount of radiation required to liberate positive and negative charges of one electrostatic unit of charge"
what exactly does this mean?
 
Physics news on Phys.org

Discussion



Ionizing radiation liberates electrons from neutral atoms. 1 Roentgen of radiation liberates 1 statCoulomb of charge per cm3 of dry air.

Recall

22.41 liters of air contains about 29 grams of air (1 Avagadro's number of molecules) at STP.

1 statCoulomb is 3.33 x 10-10 Coulombs.

About 34 eV (electron volts) of energy loss in air liberates 1 electron (1.6 x 10-19 Coulombs).

1 rad (ionizing radiation energy dose) in air is defined as 100 ergs per gram.

So roughly 1 Roentgen ≈ 0.9 rads.

Please check my math.

Bob S