cheap and easy maintenance Na(Tl) detector

The answer is that the better spectrometer depends on the applications and requirements. HPGe spectrometer has an excellent energy resolution, but lacks in sensitivity and requires low operating temperatures. NaI(Tl) detectors excels in sensitivity, but lacks in energy resolution, dead time, and the present unit lacks the ability to use digital spectrum stabilization for feedback control.

It is mentioned above and I agree with Florian:

for spectroscopy the HPGe detector (or Si(Li)) is advised due to the far more better energy resolution compared to NaJ(Tl). When doing spectrosopy you need proper energy resolution in order to destinguish close lying lines and to have small lines more efficiently sticking out of the background.

thank you dear for your replay ,

but again I think if you have the chose you choose (HPGe) because its more relabel , and in it we can find most of the radionuclides exist in the samples beside it take short time , (2 h ) of measurement in (HPGe) gives more accurate results best than (24 h) measurement in Na(Ti).

Yes, you are right;

you cannot really compensate bad energy resolution by expense of measurement time.

By the way:

accidently there is a doubling of your question here on RG:

https://www.researchgate.net/post/which_spectroscopy_do_you_prefer_NaTl_or_HPGe_detector

You should delete that second question, so that all answers remain collected in one.

It depends on your experience to select the fit detector and the type of matrix that request to analysis.

HpGe

I would prefer Nai(Tl) for Field based radiometric studies and HpGe for Laboratory assaying of radioactivity (radiometric studies).

Thank you Sengupta for your reply ,

l will be gratful if you give a practical example on your both studies by each detector to clear the idea.

Dear Nada Farhan Kadhim,

During Radiometric Field Prospecting one plots the data in the form of Iso-rad maps and then does a Trend analysis to locate potential Radioactive anomalies and the causes for the same. In case of Lab based Radiometric studies one looks for uranium, thorium and potassium concentrations (along with other radionuclides of interest) in a few pre-seolected samples based on the earlier Field studies.

Please have a look at some of our publications in Research Gate. All the best.

Dear Debashish

Thank you verey much for the explanation, l will see your reseach to get more information about what yoi say.

I agree that HPGe resolution is much better than the NaI one, but we always need to consider the application, as the scintillator efficiency is better. However, I would like to remember that the choice sometimes depends on the budget we have available and also that several isotopes decay schemes were determined with scintillators, before the advent of semiconductor detectors.

thank you Brigitte,

yes theoretically I new Nal is more efficient than HPGe , but practically I dont understand what it means.

I agree with you that choice depends on the budget we have available .

With resepct to the above discussed comparisons of energy resolutions and efficiencies of NaI compared to HPGe as well as their definitions please have a look for example at:

Article Efficiency and resolution of HPGe and NaI(Tl) detectors usin...

Efficiency of any detector is the capability to register more counts in a short period, meaning that is better for weak sources or low intensities. Resolution is the capabilty of separate closer energies. For example, a scintillator is very usefull for angular correlation experiments or for the unique determination of Cs-137 when there are no other radionuclides in the sample.

There are more choices than these two. Whenever we expect a spectrum populated with a lot of lines, we need high resolution (for the environmental radioactivity measurements, for example), thus the best choice would be the HPGe. Of course, in practice this usually means lower detection efficiency, but if the budget is high enough, nowadays one can buy HPGe crystals even with 120% relative efficiency, i.e . not only with better resolution, but also with higher detection efficiency than a 3" x 3" NaI.

On the other hand, if there is no need for high resolution but there is a need for obtaining a result with in a short measurement time, NaI is better. But there are compromises, as one can buy a scintillator with a high counting efficiency but with much better resolution than NaI, like LaBr or CeBr. If NaI has a resolution of 6% at Cs-137, LaBr and CeBr have a much improved figure, between 3.5% and 4.5%, depending on the electronics.

Thank you very much for this valuable information

dear colleagues,

thank you very much for your interest answers.

It depend to the expected results. If you want to measure many radionuclides in your sample it is better to use HPGe detector because it have a good resolution but for if your sample contain one radionuclide and you want to measure it in a short time the NaI(Tl) is better for his good efficiency.

NaI(Tl)

HpGe

Please deliver arguments, not just statements.

Both of them each one has its own applications and requirements

Both of the are same semiconductor scintillators agreed used for the same purpose. However, both have some advantages over one another. Na(T) detectors are more effective and good when it background count. This due to it ability to count at a very low dose rate with fine peaks especially for primordial. While HPGe has high resolution when dealing with irradiated samples.

Read the Book "RADIATION DETECTION AND MEASUREMENT" By G.F KNOLL

https://books.google.co.in/books/about/Radiation_Detection_and_Measurement.html?id=4vTJ7UDel5IC

If you deal with high activity samples, certainly the second one is better. It has good efficiency (count) compare with HPGe.

@Rabiu Adamu: no, they are not the same type of detectors, they are rather different in term of physics and how they work. NaI(Tl) is an inorganic scintillator, and it works by collrcting the light scintillations induced in the crystal by the radiation onto a PMT, which converts these scintillations into a current pulses with an amplitudine proportional to the energy of the incident photon.

The HPGe, on the other hand, is semiconductor diode in which the incident radiation produces charged pairs that are collected at the two electrodes of the detector. Therefore the two different behaviours in efficiency and resolution.

Radu A. Vasilache agree with you, the physics principle is different, de HGe is a semiconductor an has a better resolution but typically the NaI (photomultiplier-scintillator) is faster than HGe. Another thing to have in mind is the conditions of the application because maybe you cannot measure with the temperature conditions that the HGe needs, in this case, de Na is more versatile.

I guess, for example, if you just need to count under the spectral line a Na is ok, but if you need to define or resolve to peaks close in energy an HGe could the task simple.

It is depend on the content of radionuclides in the unknown sample that you want to analyse it. In general, HPGe is more favored in accurate analysis.

It depend to what do you measure. If you want to measure radionuclides in complex spectrum with many radionuclides. Like spectrum contains multi element after neutron activation. it is better to use HPGe detector because it have a good resolution and more accurate. but for if want to measure simple spectra contain few radionuclide you can use NaI(Tl) because it lacks in energy resolution and dead time.

The second must be used in some measurements such as neutron activation analysis. However the first can be used in other applications such as gamma ray scattering.

Both detectors can be used and type of the measuremts only define which detector is the best.

many thanks dear for your interest reply's .

Andrea Abril pleas what do you mean by ( NaI photomultiplier-scintillator) is faster than HGe ).

A. Elabd , Atef El-Taher , how can you do the ( neutron activation analysis) and what is the amount of samples required to achieve that.

Dear Hanno Krieger ,

figure below shows the different in the investigation of the radionuclides in the same sample between the both detectors .

I was taking about the time of flight

Andrea Abril

Dear Andree ,

I beg your pardon , but what do you mean by the time of flight, if you mean the measurement time of the sample , the time using Nal(Ti) is longer than the time using HpGe.

@ Andrea Abril. Can you kindly help with that clarification?

The NaI (Tl) detector has a large  detector area and therefore it has a high probability of detecting γ-radiation. The HPGe detector offers less detection efficiency compared to the NaI (Tl) detector because its detection region is confined to the depletion depth which has fabrication limitations.  Hence, Na(TI) detector is a more efficient detector compared to HPGe detector, although it has a very poor resolution. For higher energies, it is advantageous to use NaI(Tl) detector.

Dear Mostafa M. Hamed ,

thank you very much for explanation and documents.

https://doi.org/10.1016/S0969-8043(96)00118-2

http://lup.lub.lu.se/student-papers/record/2156908

https://www.hindawi.com/journals/stni/2014/186798/

DOI: • 10.1016/j.apradiso.2003.10.006

Na (Tl) meaurment time is faster than the measurment of HPGe detector. However, the resolution of HPGe detector is greater than the resolution of Na (Tl) detector.

Doufnoune RACHIDA Rachida

Dear

thank you for reply and interest information

HPGe

NaI(Tl)

I think it depends upon the sample nature and required radionuclide to be measured. If you will measure an intermediate or high gamma emitter with one or two gamma energies its better to use NaI, but if you want to measure a mixture of radionuclides with different and almost equal gamma energies you can use HPGe detectors

📷It depends on what you want to measure in practice. If what is required is a quantitative and qualitative measurement, it is preferable to use high-purity germanium (because it has a high ability to separate close energies), but if what is required is a qualitative measurement only in the sense of knowing the type of elements in the first place without interest in knowing their concentration, a sodium iodide detector is used with thallium (for its high efficiency).