Scintillation Detectors (Instrumentation Textbook)

____ is when the next pulse arrives before the pulse has returned to baseline, results in incorrect low energy

What can interact with a scintillation crystal?

The ___ corresponds to gamma rays that have undergone photoelectric absorption in the scintillation crystal.

The PMT must be shielded against stray magnetic fields, as these will alter the trajectory of the electrons.

The total multiplication factor of the dynodes is about ___

Most counts to the right of the photopeak have undergone a Compton interaction and are considered "scattered" photons

The well configuration is designed for external counting of radioactivity in organs such as the thyroid gland.

Scintillation detectors allow us to distinguish between scattered and unscattered gamma rays.

Calibration is needed to correlate _____ to the energy of the gamma rays being detected.

Which of these do NOT contribute to peak broadening?

A scintillation detector has the ability to determine the energy of the interacting gamma ray.

The valence band is at a ____ energy than the conduction band.

In a probe configuration, you have a flat-field collimator to give meaningful measurements of individual organs.

An increasing energy resolution at quarterly checks could mean everything except:

The y-axis of an energy graph represents:

the ___ collects all the electrons produced from the final dynode and emits an output voltage signal.

If your readings are higher than the expected constancy reading it could be because of everything except:

If your readings are lower than the expected constancy reading it could be because of everything except:

_____ evaluates how well a given detector distinguishes between gamma rays of closely spaced energies.

Another name for energy graph is:

A detector's _____ characteristics determine how well that scale applies throughout the energy range.

The thallium impurities create electron orbitals b/t the conduction and valence bands called ____

The ____ counts accepted pulses and tracks time.

A drawback of a single-channel analyzer is:

A _____ converts scintillation photons to electrons.

Scintillation detectors with 1 PMT are made in 2 specific configurations:

When an electron moves from the ___ band to the ____ & back down to the ground state, it releases a scintillation photon

Where must a pulse fall in relation to ULD and LLD in order to produce PHA output pulses?

Which instrument is NOT a scintillation detector?

The scintillators used in NM are inorganic ____ scintillators, often w/ small amounts of impurities.

____ is the ability to convert radiation emissions to detected signals. Depends on composition, geometry, energy window

A series of ___ multiply the small # of electrons generated at the photocathode into an electronic signal.

the _____ determines the amplitude of the pulse, which correlates with the gamma ray's energy.

The ____ provides the proper electric field to direct the electrons toward the first dynode

A well counter is not as sensitive as a GM survey meter.

A ____ boosts the strength of the PMT output signal to allow its passage through the remaining detector electronics.

The most common inorganic scintillator employed in NM is _____ activated sodium iodide.

Scintillation photons are detected by a _____ and are converted to an electronic signal.

___ is the number of scintillation photons emitted per eV or radiation absorbed

An MCA doesn't show all radiation events on an energy graph.

Cs-137 emits ____ keV gamma rays.

The well configuration is designed to measure samples of radioactive materials in test tubes.

The output pulses from the PHA are the same size and are sent on to the scaler and rate meter.

scintillation detectors generally operate in ___ mode.

The energy resolution will be larger for lower-energy photo peaks than for high-energy photo peaks

We quantify the energy resolution by calculating the

A vacuum must be maintained inside the PMT so that no electrons are lost due to interaction w/ any gas molecules.

when pulses pile on top of one another & recorded as a single event. Can cause scattered counts to be registered in PHA

Which energy is always used to compare energy resolution between detectors because of only having a 6-8% FWHM?

___ is any material that can release a photon in the UV or visible-light range.

Which is NOT a type of pulse height analyzer?

_____ allows us for better counting of photons at close energies

The ULD and LLD are set by the operator & are related to the ___ of the photons being measured.

The ____ of the PMT determines the potential difference b/w the dynodes & the final size of the PMT output pulse.

Scintillation photons are converted to an electronic signal by the ___

The X-axis of a energy graph represents:

We deal with ____ by setting the detector to look at a range of energies around the photo peak.

Most ___'s work by assigning the event to one of a series of predefined bins or channels based on the signal's size

We set up an ____ to include most of the photo peak and exclude everything else.

A 1% change in the high voltage results in a 10% change in the ____ size.

An ____ amplifies & shapes the preamp output signal by a variable amount & is controlled by course & fine grain controls