What is a pulse height distribution?

Pulse height distribution data which is defined as the distribution of the energy deposited in detector volume gives some information about the profiles of emitting radiation source. This non-Boltzmann quantity can be calculated by numerical simulation of the radiation interactions in the detector and its environment.

What is pulse height spectrometry?

Pulse-height spectrometry is used to examine the amplitudes of signals (electrical current or light) from a radiation detector to determine the energies of radiations striking the detector, or to select for counting only those energies within a desired energy range.

What is pulse height discrimination?

An offline digital pulse shape discrimination (PSD) method was used to distinguish neutrons from gamma rays [4]. This method is based on a standard charge integration technique, which calculates the ratio of the integrals of two different pulse intervals.

What is the function of a pulse height Analyser?

A pulse height analyser is an instrument used to analyse the frequency distribution of the spectrum of photon energies that are captured by a gamma camera. Energy windows are selected to only allow certain photon energies that fall within a preset range to contribute to the output pulse.

How does a PMT work?

A photomultiplier tube, useful for light detection of very weak signals, is a photoemissive device in which the absorption of a photon results in the emission of an electron. These detectors work by amplifying the electrons generated by a photocathode exposed to a photon flux.

How does pulse height analysis help in the detection of in vivo radioactivity?

Pulse-height analysis on Z pulses allows us to select the pulses of the desired energy. Two important attributes of the Z pulse are linearity with γ-ray energy and its spatial independence (Z pulse-height should not depend on the location of the point of light production in the crystal).

What is backscatter peak?

Backscattered peaks. Close inspection of a gamma-ray spectrum may reveal a wide peak with energy <250keV which does not correspond to a known photon from the source. Such a feature, termed a Backscatter peak, is due to gamma-rays which first interact by Compton scattering with the shielding.

How does pulse discrimination work?

The pulse shape discrimination techniques are based on the fact that neutrons and gamma rays give different pulse shapes when interacting with the neutron sensitive organic scintillators. The neutron interaction results in a slower timing signal than the gamma-ray interaction.

How long is scintillation after excitation of molecule?

In gases, the scintillation process is due to the de-excitation of single atoms excited by the passage of an incoming particle (a very rapid process: ≈1 ns).

How does pulse-height analysis help in the detection of in vivo radioactivity?

What is PHA window?

The PHA Risk Assessment window functions the same as the standard Risk Assessment interface, with some exceptions: The Risk Matrix and risk rank values are populated automatically with the corresponding values from the Risk Assessment record that is associated with the Hazards Analysis.

How is the pulse height spectrum related to energy?

…channels matching their amplitude, a pulse-height spectrum is accumulated that, after a given measurement time, might resemble the example given in Figure 3. In this spectrum, peaks correspond to those pulse amplitudes around which many events occur. Because pulse amplitude is related to deposited energy, such peaks often correspond to…

Which is a major factor that distorts the pulse height?

The major factor that distorts the pulse height is the variation on the number of photoelectrons released at the cathode 137 Cs would release, on the average, an initial 2000 photoelectrons (3 x 662) Variation of this value occurs when Poisson distribution is applied

What is the analysis of pulse height spectrometry?

The Analysis Pulse-Height Spectrometry Pulse-Height spectrometry examines the amplitudes of signals being received from the detector which arrive at the PHA to be accepted/rejected Description of how energy is transferred in a Na (I) crystal.

How are pulse heights generated in a crystal?

Pulse-heights are generated from photoelectric interaction within the crystal that creates a pulse heights that are proportional to energy deposited in the crystal Ideally this produces a single narrow line in the pulse height spectrum, defined as the photopeak