GAMOS tutorial Shielding Exercises

1. GAMOS tutorialShieldingExercises Pedro Arce Dubois CIEMAT http://fismed.ciemat.es/GAMOS Introducción a GEANT4

2. GAMOS radiotherapy tutorial Shielding simulation Exercises Ex. 1: basic study of shield effect Reduction factor of a shield Effect of shield plate Ex. 2: Shielding of an Am-Be source Ex. 3: Flux and equivalent doses Ex. 4: Activation studies The exercises are sequential Use the commands of the previous exercise (only change what indicated)

3. GAMOS radiotherapy tutorial Exercise 1a: reduction factor of a shield Geometry: a plate of concrete (G4_CONCRETE) of surface 1 m X 1 m Beam of 1 MeV neutrons along the positive Z axis hits the plate QGSP_BIC_HP physics Calculate the width of the plate so that only 1/10 of the neutrons traverse it

4. GAMOS radiotherapy tutorial Exercise 1b: effect of shield plate Use the concrete shield defined in problem 1a Make an histogram of the energy spectrum of neutrons and other types of particles that traverse the plate i.e. exit the plate by the positive Z face Store in a file the information of the particles that exit the shield by the positive Z face: Event ID track ID, particle name, energy, position X, Y & Z, direction theta & phi

5. GAMOS radiotherapy tutorial Exercise 2a: Shielding of Am-Be source Place a point-like Am-Be source of 1 mCi inside a sphere of lead of inner radius 5 cm and outer radius 6 cm Use the QGSP_BIC_HP physics list Get the flux of neutrons and gammas that exit the sphere by the outer surface Get the number of each type of interaction of the neutrons from the Am-Be source in the lead sphere

6. GAMOS radiotherapy tutorial Exercise 3a: Flux and equivalent doses Place a point-like Cf source of 10 mCi in the centre of a room of 8 X 8 X 8 m, with 20 cm of polyethylene + 50 cm of concrete walls, floor and ceiling Use a concrete of density 2.289 g/cm3 and composition: Mg 0.5670 % Mn 0.02882 % O 52.19 % Al 3.968 % Pb 0.2016 % H 0.52 % Cl 0.3352 % Use the QGSP_BIC_HP physics list Get the neutron flux as a function of energy at a point 10 cm after the room walls at the height of the source, and also the neutron personal equivalent dose, H* and ambient equivalent dose Hp(0,0) Get the gamma flux as a function of energy and of the physics process that created the gamma at the same point • K 1.185 % • Si 27.79 % • Ca 11.30 % • Na 1.057 % • C 0.2271 % • Fe 0.63 %

7. GAMOS radiotherapy tutorial Exercise 4a: activation studies A beam of 18 MeV protons entering in a target of water enriched in 18O (100 %) to produce 18F Beam shape has gaussian cylindrical profile of  = 5 mm The proton source is at (0,0,0) Water target Cylinder of 1 cm radius and 5 cm length Walls are 1 mm of copper At entrance there is a circular aluminum window, 0.5 mm thick and radius 20 mm Placed with axis along X, touching the source, extending in the positive X Use as physics list QGSP_BIC_HP Irradiate the target for 5 min Calculate the activity of all isotopes produced Calculate after 10 min more the dose at a point 10 cm apart from the front wall of the target