Estimiting the half - value layer thikness - Lab Report Example

INTRODUCTION Ionizing chambers are generally utilized in detection of the high levels of x-rays but are not fundamental in measuring low x-rays levels. They possess frequency that are relatively expensive than Geiger counters and can be utilized to directly quantify the underlying magnitude of an x-ray field as they possess a linear response in regard to lower x-ray energy less than 100kev approximately linear response above 100keV. Shielding as control method is mainly utilized in reducing the external radiation hazard.

The suitable material to use depends on the type of radiation and its energy. Alpha particles are easily shielded thus they will present no external radiation hazard. The thickness of material of 50% of the underlying incident energy has been attenuated and known as half-value layer (HVL) and it is normally expressed in either mm or cm. Photo energy is normally dependent on the increasing energy of the stream of photons thus resulting to increase in material HVL. OBJECTIVES: Estimating the half - value layer thickness for wood and aluminum with different sourcesMATERIAL AND INSTRUMENTThe main materials and instruments that were utilized in the experiments includeWoodAluminumCrucible (material x)Geiger-Muller counterCaliperCS-137Sr-90METHODOLOGYI.

Setting The experimental equipment was outlined as shown in the figure below. The radioactive sources are encapsulated in thin metal shield that absorbs beta radiation accompanying the decay. The alpha radiation is solely slightly attenuated but the beta radiation. Every source is contained within a cylindrical lead radiation shield in order to eradicate eminent health hazards The underlying counter is then mounted within the shield lead to counter unwanted radiation within the laboratory. The thickness of the absorbers includes:Al: 20 mm for every slabWood: 4mm for every slabWater: 10mmII.

ProcedureGM-counter was assembly with the assistant of the lab technicianBackground count rate were measured three timesThe shield with the underlying source to be utilized was placed within the setup. Cylindrical pin was that sealed from the sourceBackground pulses was counted without absorber within the beam(x=0) for counting time specified. Another slab was added and the series of measurements were mounted on 10 slabsWood slabs were removed and the measurement series were repeated for 5 aluminkium slabsAluminium slabs were removed and mounted on the Plexiglas cylinder filled with demineralized der and windowsSequence of measurement was repeated using other two sourcesMeasurement was performed to verify the statistics of the prevailing pulse counting (cf Data examination).

Cs-137 source was used and mounted on a single lead slab amidst sources and corresponding GM-tubeRESULTS: X-rays are normally absorbed in an exponential manner A= A0e(-0692h/H where A0 is the original x-ray intensity, A is the x-ray intensity transmitted via an absorber of thickness x,e is the natural logarithm system and µ is the slope of the underlying absorption curve(normally linear attenuation coefficient measured in per cm). Linear attenuation coefficient is associated to the corresponding density of the absorber.

The half-value layer is normally the thickness of the radiation absorbing material that reduces x-ray intensity by ½. Number of shielding Wood AAluminum ACS-1373A30Sr-903AA The equation A= A0e(-0692h/H) = WoodAluminium CS-13751Sr-90Conclusion Based on the value from the slope of the natural log plot, the thickness of aluminium and wood in regard to reduction of the gamma beam intensity from the radioactive Cs-137 source to the corresponding its initial intensity. The main human error was random error from the experimenter thus I can be controlled by taking many readings.

For a thickness of 2HVL the corresponding photon intensity was reduced by ¼ of the initial value whilst for a thickness of 3 HVLs the photon intensity was reduced to 1/8 of the initial value. Moreover, the shielding thickness 7 HVL s was required in order to reduce the photon intensity to below 1% of the initial value. Thus, it is always advisable to determine the quantity of the shielding to utilize to property attenuate x-ray radiation. The result depicts that radioactive sources are normally encapsulated within the thin metal shield and mainly serve the purpose of absorbing beta radiation.

Moreover, alpha radiation is slightly attenuated as compared to corresponding beta radiation. The result is normally affected by the number of shielding slabs and corresponding distance. Cs-137 source was used and mounted on a single lead slab amidst sources and corresponding GM-tube. Ionizing radiation inflicts damage on the materials penetrated and the degree of damage is associated to the quantity of the energy deposited rather than the underlying charges. The distance that radiation travels is mainly dependent on numerous factors such as type of radiation, energy of the radiation and the corresponding material that the radiation passes.

Work CitedGupta, Tapan K.. Radiation, Ionization, and Detection in Nuclear Medicine. Dordrecht: Springer, 2013.