How do you calculate energy resolution?

How do you calculate energy resolution?

1. Energy Resolution is the ability of the Detector to accurately determine the Energy of the Incoming Radiation. Since no camera system is perfect, no system is capable of determining precisely what energy photon struck the crystal.
2. If Gamma Camera Energy Resolution = 10%
3. %Energy resolution = FWHM x 100 /photo peak.

What is the efficiency of NaI TL scintillator?

The scintillation efficiency of a NaI(Tl) crystal to electrons in the energy range up to 70 keV has been deduced from the photon-excitation efficiency recently measured by the author. The efficiency curve has a peak at 7.8 keV and shows the highest values in the results ever reported in the region below 25 keV.

How is detector resolution calculated?

Re is obtained from the peak full width at half of the maximum height (FWHM) using the following equation: Re = FWHM / E (%), where E is the related energy of the peak. Re is better (i.e., its % value is lower) for higher energies.

How does NaI TL detector work?

The basic principle is the same for every scintillation-type detector: when radiation strikes the scintillator it causes it to give off photons of visible light (that’s the scintillation part). When the photon hits the photocathode it causes an electron to be ejected from the photocathode.

How is counting efficiency calculated?

Efficiency (E) is computed by dividing the measured net counting rate* in counts per minute (CPM) by the sample’s activity in decays per minute (DPM). This will yield a fraction that is less than 1; the detector only counts some of the radiation that is given off by the source.

What is resolution of NaI detector?

The energy resolution of a 3 ʺ × 3 ʺ cylindrical NaI(Tl) detector is usually measured using 662 keV gamma rays emitted by the 137Cs source. The energy resolution at this energy is around 6–7% [2].

Is NaI a scintillator?

NaI(Tl) Scintillation Crystals Sodium Iodide crystals have a very high luminescence (scintillation) efficiency and are available in a wide variety of sizes and geometries that makes it the most widely used scintillator.

How do you calculate Scherrer?

Scherrer formula is used to calculate the average size in vertical direction of crystal. D=Kλ/(β cos θ). For cubic crystal structure, K =0.94, λ is wavelength of X-ray. d = the full width at half maximum intensity of the peak (in Rad) – you can calculate it using Origin software.

How is FWHM value calculated?

FWHM can be determined as the distance between the curve points at the peak half maximum level. On a data graph, draw a vertical line from the peak maximum to the baseline. Measure the length of this line and divide it by 2 to find the center of the line.

How is the energy resolution of the NaI detector determined?

For these purposes the absolute efficiency and the energy resolution of the NaI (Tl) detector have been determined experimentally at 511, 662, 835, 1173, 1275, and 1332 keV energies obtained from 22 Na, 54 Mn, 60 Co, and 137 Cs radioactive isotopes. 2. Experimental Methods

Why is the energy resolution of scintillation detectors important?

A good energy resolution is of great importance for most applications of scintillation detectors. Thus, its limitations are discussed below; which arise from the non-proportional response of scintillators to gamma rays and electrons, being of crucial importance to the intrinsic energy resolution of crystals.

Is the NaI crystal the same as a scintillator?

•137Cs spectrum in NaI crystal same in plastic scintillator •the photopeak is not seen with plastic scintillator; that’s the Compton edge •organic scintillators: low density; just C and H; photoelectric effect goes as Z4 Figure 4.13: Cs-137 spectrum taken with 2m X-Plank.

Which is the scintillation decay mode in Nai?

Two scintillation decay modes in NaI (Tl) (the intense fast component of 225 ns and the weak slow component of about 1 μs) have opposite non-proportionality characteristics versus the deposited energy.