Gamma Spectrometry - Science method

A new version for Windows was uploaded yesterday. This version has isotope identification.

Use the background area under peak 1 as shown in the figure. It is possible to perform iterative fitting to refine the background, but unlikely you will reduce the uncertainty in the estimate to an important degree.

There could be several reasons why you're encountering difficulties calculating the K/eTh ratio or F-parameter in your gamma-ray spectrometry data for K-enrichment delineation. Here are some possibilities to explore:

By systematically investigating these potential causes and seeking additional resources, you should be able to identify the source of your problem and successfully calculate the K/eTh ratio or F-parameter for your K-enrichment delineation project.

To measure radioactivity in the human body it is necessary to have a good radiation shielding around the detector and the subject. The shielding is in this case built of massive steel stabs of naval armour- plate forming an iron room The iron room is ventilated with filtered air.

as a result the detector is sensitive to gamma-radiation with energies above 50 Kev and supplies information about the energy of the gamma photons, which makes it possible to identify the gamma emitting isotope measured by the spectroscopy. A certain hour measurement offers the possibility of detecting of a 100 % gamma emitting isotope distributed in the nail at the gamma energy is above 50 Kev.

does the shoulder appear in the total energy peak in the HPGe gamma spectrum of certain samples, there are two probabilities, if the problem in the HPGE detector, adjust it if not it is problem due to the high activity of the sample therefore it is necessary to remove the sample at the level of the detector to eliminate the peak sum phonomene

MARION technology

Gamma spectrum analysis is regarded as a fast, reliable and non-destructive technology on determining the type and intensity of radionuclides. It is widely used in nuclear physics research, geological exploration, environmental assessment. Under the certain condition (detector, electronic components and measuring environment), the data obtained by different unfolding algorithms have different results. The accuracy of qualitative and quantitative analysis of radionuclides is determined by gamma spectrum unfolding technique https://www.sciencedirect.com/science/article/pii/S2211379718334223

Dear Sir,

I think following person can help you.

Vicky Bhosale

9833659640

Electronic Enterprises (India) Pvt. Ltd. Mulund(E). Mumbai.

Phone: +91-22-25639904 / 25636011

Web: www.eeipl.in

Good and interested question Nada Farhan Kadhim

Hi Sebastián Alejandro Sarasti,

The most significant difference is the width of the photoelectric peak at 662 keV. This width occurs after gamma-ray energy is transferred to the scintillator crystal. Your simulation probably may not include this part.

The number of scintillation photons generated, when 662 keV is totally absorbed by the NaI:Tl crystal, is statistically distributed. It is also a stochastic process whether each scintillation photon is successfully detected by a photodetector (photomultiplier tube or semiconductor device) or lost.

There are two ways to improve the distribution. One simple way is to assume the energy resolution of the detector (crystal + photodetector) and perform a convolution with your results. You can fine the typical energy resolutions in literature: typically ca. 7% [*].

Another detailed method is to add, if necessary, simulation to track the behavior of the scintillation photons.

The other differences seem to be related to Compton scattering; since the NaI:Tl crystal is sealed in a package, some of the energy may be lost by Compton scattering in the package before it enters the crystal. Then, the gamma-ray energy is not 662 keV but less than 475 keV for the detector. Similarly, Compton scattering from surrounding desks, walls, and other objects may enter the crystal and increase the proportion of that component of the experimental data.

If you are using a typical Argon-based ICP-MS, even if the operating software permits you to measure isotopes of m/z = 40 (K, Ca and Ar), I think you will struggle to accurately quantify K-40 as it is going to be overwhelmed by the Ar-40 signal from the plasma.

I suspect you will have to use a different technique that doesn't use Argon plasma.

Vinicius Antunes

Richard Fortin

Joseph L Alvarez

Eugene Druker

Hadi Shahabinejad

Hello everyone!

With respect to this discussion, and in the case of gamma-spectrometric surveys, I have to add that one of the first things you should observe is your statistics. Yes, negative values ​ exist, but they tend to not be that frequent.. A quick analysis on the database histogram will show you that the proportion of negative values ​​compared to your total database is really low.

At least here in Brazil, regarding to the airborne geophysical data from the Geological Survey of Brazil, these values ​​usually represent a tiny 1% of the total data. The spatial distribution of these "incoherent" data is another factor to be considered. If the data is spread over a large area, it can represent mere noise. There are also drainage sites, dams, large rivers and lakes, where values ​​tend to fluctuate between 0. Another factor to take into account is if only one of the channels has this "incoherent" value for the point or all channels (K, Th, U) have it, because if it is only one channel, the most likely hypothesis is that it is just a noise or "fluctuation" of detected values close to zero ... In these cases you can declare the points as DUMMY and just move on in your data processing flow.

If the negative points are represented in all your channels at the same time and for the same coordinates, and are spatially concentrated in the same region... Well.. in this case you must investigate the cause. However, this will rarely be the case.

If your "inconsistent" values ​​represent somewhere between 5 - 10% of your database, probably something in the QA / QC during the data acquisition occurred, I mean, some technical failure or difficulty. In this case, the data set is under suspicion. It does not mean that the entire database would be useless, but it does mean that your analysis needs to take this factor into account when drawing conclusions or making predictions.

Another factor that can make negative values ​​appear on your maps, even if you are careful to@ declare values ​​as DUMMY in your database, is the interpolation method. Imagine two points close to zero and the interpolator, to "connect" them, does it by means of a polynomial curve of degree 2 instead of a straight line. Somewhere the curve may fluctuate to negative values ​​... and then there may be some remnants on your map. In this case, check the map statistics (histogram) and review the possibility of declaring the inconsistent points as DUMMY.

Best regards,

Frederico Sousa

Researcher in Geosciences - Geophysicist

Geological Survey of Brazil

We can calculate Net count rate uncertainty in gamma spectrometry Technique by using square limit equation, you should calculate the total error ( systematic and theoritical) before calculate Activity of samples

as cited in ISO 8529-1, you use the conversion factor 391 pSv.cm² for Am-Be neutron source

Hello,

For natural radionuclides you can have a look to :

van der Loeff, M. R., & Moore, W. S. (1999). The analysis of natural radionuclides in seawater. In Methods of Seawater Analysis (pp. 365-397). Verlag Chemie Weinheim.

availble online at:

Best regards.

Matthieu

Coincidence summing is called for when your detector is not able to tell two separate gamma-emissions (in quick succession) apart from each other, thus revealing one (apparent) larger energy that is the sum of the two above-mentioned emissions. This phenomenon can be either 'true' (depending on decay scheme, since the source emits a cascade of gamma rays) or 'random' (when two different nuclei emit radiations that are closer in time than detector response time).

Coincidence summing is usually minimized by the implementation of: 1) fast-response detection; 2) large separation between source and detector (if compatible with activity level); 3) sequences of single sources rather than multi-emitters; 4) Compton-suppression systems (anti-coincidence detector ensembles surrounding main detector).

Coincidence summing can be mathematically accounted for, but slightly-more-than-trivial geometries usually require Monte Carlo approaches.

Take a look here:

Dear M.M.Mahfus

Thank you very much for interest information.

There is an empirical equation can be used for the required correction based on the natural abundance of Uranium and the activity concentration of U-238. Practically, more details is represented in the following article:

Hopefully, it will be helpful for you.

yes

The attached image is of a Cs-137 spectrum with NaI.

Is this an example for any spectrum?

Are you seeking an estimate of MDA for reporting purposes, to state that nothing was found in the region above the detection limit?

A detection limit should be for a given radionuclide for a given analysis matrix. The actual background is determined from the matrix and its sources of noise in the peak region.

A rough background for a non-specific photo peak would be the total counts in the region of interest.

The equation you are using for the MDA is inadequate at few total counts.

Fahad Ibraheem Almasoud

dose this rule apply to all radionuclides.

Thank you for that answer. In principle, That is what I am doing now. However, with this method only, I lose all CAM parameters. Therefore I use the "strip" method on the new CAM file afterwards and calculate original spectrum - original spectrum + new spectrum. By doing so, I transfer all CAM parameters to the new spectrum.

thank you very much Dr. Mushtaq

Dear Dr. Said,

I think that your question implies that your are planning to establish elemental analysis laboratory of trace heavy elements.

As mentioned by answers, it is important to know what elements you are looking for and what materials you are intending to analyze.

I recommend XRF technique. It is multi-elemental (typically from sodium (Na) to uranium (U)), non-destructive and direct elemental analysis technique. Wide range of materials can be analyzed - in solids, liquids, powders and thin films - at detection limits starting from 100% down to less than parts-per-million (ppm) levels.

Commercial XRF spectrometers have small and simple design. Its operation costs less than other known elemental analysis techniques like ICP-MS and AAS. These systems support patch analysis, i.e. perform both data acquisition and analysis for several samples automatically and quickly. Normally, no sample preparation procedures are needed and samples can be analyzed as received.

Dear Gideon

check these links. hope be useful.

Greetings Gilberto,

The following article has results of findings in the oil and gas industry:

The NORM study in the oil industry is starting in Venezuela. We have worked on the chemistry and radiochemistry of oil production waters and scales, emphasizing the exhaustive study of their chemical properties. Our ideal is to build a NORM map in the oil industry, in which the geological, chemical and radiological characteristics are present; This topic is extensive and interesting.

In addition, a study that contains analytical interest of the waters, is of great help to visualize the behaviors of the radiometric analysis. Unfortunately, analytical quality analysis in oil production waters is not a simple job. And radioactivity analysis in water is costly from the operational point of view due to the volume of water to carry out radiochemistry.

Best regards.

Ender Araujo

you could use gamma spectrumitry of analysis areosol fillter but you will needed standard source for calbration your detector used in analysis gamma spectrumetry .

there are alot of equepments used to analyses alpha beta radio nuclide for areosel and give you good quality of analysis for air monatering like iCAM Alpha/Beta Air Monitor fom canbirra

Actually the ligand coated on the resin is 40% (w/w) so I have it. But I do not know the formula by which I can calculate the constant.

All of the samples I used were measured with radiotracers so their quantity is low enough and can be calculated in moles easily.

On the other hand I can not measure pH first because the samples are long gone and new ones will take to much resources.

Bi-Directional is a technique for roughly parallel lines. It is 1D method, it cannot use tie lines. It creates grid lines (columns, rows) independent of each other, which may lead to discrepancies and visible artifacts, especially with nonlinear (Akima) interpolation. Its fitting in data nodes is not obvious.

Minimum curvature gridding method creates a minimum curvature surface

to the random data points. It is 2D method, it uses all the input data. This surface is the smoothest surface that fits the given data values. The method is linear. Its fitting in data nodes can be regulated.

I would use minimum curvature method in any regular situation.

You can find much more information (for much more time) searching

documents at http://www.geosoft.com.

Normally, potassium channel data become noisy when either thorium or uranium or both concentrations in ground are high. This high concentrations make enough contribution to K channel through Compton scattering. Now uranium measurement is done through Bi-214 emissions which is large when radon in the area is high. So you need to look into radon concentration also.

In the photoelectric effect, the photon transfers all the energy to the atomic electron. The atomic electron must be tightly bound so that the photon can transfer all the energy to the atomic electron (Head-to-head collision); otherwise Compton scattering occurs.  Hence the photoelectric effect occurs with tightly bound electrons especially K-shell. The Binding energy of the K-shell electrons, which are most tightly bound, decreases for low Z elements. So the photoelectric effect is reduced for low Z media.

I glanced through the reference cited by Joseph L Alvarez. Though old, it shines as one the best extensive and educative article covering not only physics of gamma ray interactions, with reference to NaI(Tl) crystal but also methods of spectrometry with a huge compilation of decay schemes of practically all the radionuclides and analysis of their gamma ray spectrum, taken with this crystal of various sizes connected through amplifier to a multichannel analyser spectrometer. I am seeing this for the first time and it is deeply impressive. But for obtaining excellent energy resolution particularly at low energies, the latest ones using HPGe detectors are preferred. The spiky peaks at all energies obtained with this system are superior to the broadened peaks for the NaI(Tl) system. The bulky liquid nitrogen cylinders necessitated for this system to reduce noise have now been replaced by portable coolers for short term use and battery-operated spectrometers with built-in coolers are now commercially available. Papers comparing the resolution of these two systems may be accessed from nuclear instrumentation journals. The use of HPGe system for whole body counting enables measurement of low activities of gamma emitters in the body with excellent resolution. Of course, they are more expensive.

The package NMF-90 (including STAYNL) can be downloaded from the URL given at the end of my yesterday message. The "diskettes" mentioned in the section Installation are obsolete, therefore you shall use pendrives instead of those. 

Since the time of development, of NMF-90 the MS-DOS operating system became not available. Nevertheless,  there is a program CMD.EXE in the directory C:\WINDOWS\system32 (Windows XP and Windows7) running of which the environment will be similar to the MS-DOS environment. I can run the programs of NMF-90 starting CMD.EXEf irst.

The code SANDBP is for restricted distribution in Hungary, I cannot supply it.

I'm waiting for your questions.

E. J. Szondi

Follow the assumption that Ra-228 is in equilibrium with Th-232 and Th-228 is in equilibrium with Ra-228. A well-sealed sample will have Ac-228 in equilibrium with Pb-212. The average of Ac-228 and Pb-212 is a good estimate of Th-232 when Ac-228 concentration is nearly equal to Pb-212 concentration (within measurement error).

The solubility of Ra and Th are substantially different. Many situations exist that have Th-228 not in equilibrium with Th-232. The measured concentration of Ac-228 will be different from the measured concentration of Pb-212 in a well-sealed sample. The average of the Ac-228 and Pb-212 concentrations is not a good estimate of Th-232. Use Ac-228 as the estimate for Th-232. 

In principle, there is no sense in talking about a "nucleus" as such, if the system has not enough time to equilibrate its internal temperature. 

The very short "half lives" in the order of 10e-21 in the chart of nuclides do not correspond to measured lifetimes of certain nucleon ensembles but are calculated from line widths of resonances (lifetime/linewidth correlation as a result of the uncertainty principle).

I fear Paula and coworkers mismatched the instrument's type, AlphaE is battery powered an with at least under that profile it seems to be very, robust.

As to "NOISE", I never saw that message, having used the instrument in several environments with high acustic noise, high humidity and so on.

A first question is: are you sure your instrument is measurring only radon or could be present other dispersed isotopes in air?

Another source of noise in the detector could be mechanical vibration, which could be or even not, induced by acustic noise since the instrument is very light.

The issue is enteresting, if I have news I'll write.

It is highly recommended that all day the detector is on high voltage. This makes the crystal is not degraded (It is not proven, is completely empirical my sentence). We have detectors of 25 years with continuous high voltage and they never problems.

It is unlikely that you will be able to link (U,Th,K) to the climate. Why do you think you could? If you have been collecting (U,Th,K) data with respect to climate, you must have had an intent. Tell us something about your plan and data, then, maybe, we could make some suggestions. Precipitation would be the single possible connection.

Thank you everyone...

Dear Guembou,

You must select CSV output in your analysis manager. The code specific to the output format must be included in your analysis manager declaration. Next, code extracted from B4 example (B4Analysis.hh) is shown where the selection of the output format takes place uncommenting the line corresponding to csv format.

#ifndef B4Analysis_h

#define B4Analysis_h 1

//#include "g4root.hh"

//#include "g4xml.hh"

#include "g4csv.hh"

#endif

Best regards,

Santiago

In my case it is not specified , don't know why...

Just let you know that Ac-227 calibrated solution is available.

The answers by Hanno, Erik, Raymond, and Phillip are correct. The multiple surfaces of a powder cause multiple refections of the emitted light at the multiple surfaces. Note that a black powder can appear to be white, that is why a scratch on a black surface is particularly visible. Many single crystal detectors use a powder as the reflection medium. 

Bicron made shock resistant NaI detectors of various shapes by forming the detectors using granules of NaI. The gaps between the granules were filled with a plastic having the same index of refraction as NaI. The resolution and efficiency was very close to single-crystal NaI.

A scintillator powder must have a filler with matching index of refraction if used as more than a thin layer. 

According to the decay scheme of NNDC the level 7/2- level at 126-keV is populated only 1.3e-7% of the time and not 100% as you indicate.

Almost 100% of the 55Fe decays directly populate the ground state of 55Mn. So, one would not expect to see many 126-keV transitions.

As an aside the total internal conversion coefficient for a pure M1 of 126 keV in Mn is 0.01652 (see http://bricc.anu.edu.au/index.php) so it does not affect the gamma-ray intensity by much. The lack of 126-keV transitions is simply because the level is not

populated.

1 Gy/min to 2 Gy/min is normally used dose rates, presently very high dose rates are also used in pulsed mode.  

Difficult to specify this without knowing other parameters. First, if you only need cps and not spectroscopy, then a better option would be to use a plastic scintillators, as these are much more sensitive and significantly faster than NaI.

Then, in order to know the volume of the detector you need to specify:

- the height from which you measure

- the ground speed

- the required MDA

To give you an image, with a 3" x 3" NaI detector you expect about 3 kcps per microSv/h. A 100 mCi Cs-137 source will give you roughly 280 microSv/h at 1 m distance, which will go down to about 20 nSv/h at 100 m distance (if you take into account also the air dispersion and absorbtion). This means that you basically cannot spot this source from 100 m, with the 3 inch detector, if you just fly by, you will need a much bigger and sensitive detector. Also, you cannot simply use counts, you need somehow a system that will do some background substraction in a dynamic way, otherwise you will get a lot of false positives and negatives.

The photon interaction is the transfer of energy to a bound electron, the electron is freed and moves rapidly through the crystal. The electron loses energy through multiple interactions. This total energy is collected as a single pulse that is proportional to the energy deposited. The information is not lost because the transfer to the conduction band is not one transfer, but many. 

The same is true for an NaI crystal except it is the total light produced by the electron passing through the crystal.

Yes, you can use single (SEP) and double escape peaks (DEP) for energy as well as for efficiency calibration.

Using SEP and DEP in energy calibration is easy, you basically get two more peaks per transition with known positions. Also useful to quickly check your energy calibration at higher energies (>4 MeV), as you will see a "triplet" of peaks that should have a distance of 511keV.

However, at an γ-ray energy of ~2.7 MeV the SEP and DEP efficiency is very small. If you want to determine this efficiency, i would recommend using a source with higher (and more) energies, e.g. ⁵⁶Co, as the shape is very different (see attachment). This results in three "independent" detector efficiencies at high energies.

The actual cost of a passive radon measurement campaign depends on many factors but basically on your relation with the dealers so I have no suggestion about this;

However, E-perm system is available also in a version usable for 3-7 days instead of a minimum of 30 days of trace detectors such as CR-39 (e.g. Radosys Ltd).

The long term version of E-perm  claims to be usable at higher doses (integration time*concentration ) than trace detectors but I have no direct proof about this.

The e-perm system is theoretically subject to discharge caused by strong electric fields and other environmental factors. Moreover once you read an e-perm the dose value is lost while a trace detector can be stored (in principle) indefinitely for future recording.

Another non negligible issue is that trace detectors are lighter and smaller than e-perm which is of some relevance if you have to deploy  a large number of detectors in some environments.

I started annual radon monitoring in an important road tunnel in year 2000  with e-perm and swithched to trace detectors in 2003

It also depends a certain amount on the particular drone aircraft you intend to use.

Some of the very small UAVs currently being used, in Fukushima for example, can only lift 1-2kg at best. Whatever you put on such aircraft is going to be limited to dose rate only.

There is at least one aircraft system in use with a 3-5kg payload, which is enough for a small (2x2" or 3x3") NaI(Tl) or Cs(I) detector. If you are investigating relatively simple mixtures of radionuclides (eg: naturals and 134Cs, 137Cs, or 60Co) these detectors will give adequate capability of nuclide specific mapping. If you need to know what's there without any prior information then you'll need the spectral resolution of Ge or CZT - but you then have very little sensitivity. If you have the money, a CeBr or LaBr detector should be a reasonable compromise between sensitivity and spectral resolution.

We recently flew a mid sized NaI(Tl) system that would be available for the larger drones (with 20-30kg payloads), and this has given good results even at 500m over parts of the Fukushima deposition. 

Rather than answering your question in frequency, it would be more realistic to answer in energy, simply the frequency is so high that gamma ray behave more like a particle (photon) than a wave. The CGRO and other satellite experiment can detect gamma ray only up to several 100s GeV or < 1TeV = 1.E12 eV. Higher than that, the flux is so low that satellite instruments loss detection power or their discrimination power to separate gamma from much higher flux of cosmic rays. The Ground gamma ray telescope can detect gamma photons interaction with atmosphere via indirect measurement. The highest energy of gamma ray  of those experiments can reach approximately 1.E14 eV, in terms of frequency ~ 2.4E28 Hertz.

You stated that the rock you tested has the expected U238/U235. Examine the rock spectra for other helpful energies. You can develop your own calibration standard using the rock.

How does the U238 concentration compare for soil and rock?

How did you prepare the soil samples? Grind and well mix? Did you seal and store for 30 days to determine Ra226?

Do you have the resolution to numerically resolve Ra226 and U235 peaks?

Do you have soil at several depths in the same location?

DU contamination is possible from other than military usage. DU is used for radiation shielding and aircraft counter weights. 

See attached file.

Well, yes, but you will essentially be building your own MCA. You'll need to amplify and Gaussian-shape the pulses from your photodiode, then use a peak detect & hold circuit followed by an ADC triggered by the peak detector. Your Arduino can then bin the pulse heights into a histogram. If you have high activity source you will need to do something about pulse pileup (overlapping shaped pulses looking like one big pulse, which will distort your spectrum). From memory Atmel microcontrollers usually have internal 8 or 10 bit ADCs built in, so you won't get an incredibly high resolution, but should be enough for basic spectroscopy with a scintillator.

The spectroscopic amplifier is where you need to be really careful to minimise noise in your design. Your shaping time needs to be carefully chosen to match the detector's capacitance (there are lots of papers which talk about this, including application notes from various detector and instrumentation vendors) in order to minimise noise. Spieler's lecture covers this pretty well (look in particular around page 40):

HPGe detector efficiency (number in %) is usually compared the efficiency of 3 inch NaI(Tl) crystal @ Co-60 photopeak (1332.5 keV). So sometimes this value may be higher than 100%. 

On internet you will find the book "Genie2K Customization tools manual". All the answers you need are described in here.

The simples approach is:

1. Calculate average counts number per single channel for both, lower and upper background areas.

2. Make average of the two just calculated numbers - that's the average background (per channel) for all the peak region.

3. Multiply number from point 2 by number of channels in the peak - that's background of your peak. Subtract this number from total counts for the peak to get the peak net counts.

4. peak uncertainty = sqrt(peak net)

5. background uncertainty = sqrt(bacground counts - see point 3)

6. detection limit is usually defined: If measured peak (net) is bigger than 3*standard uncertainty of bacground it can be assummed as detected peak.

This gives that peak net should be greater than 3*sqrt(bacground) to be accounted as real peak and not backround fluctuation.

However to be able to quantify the analyte the peak should be greater than 3*detection limit calculated as above.

Some more details e.g here:

Hi, I suggest you to read the work of my colleagues: Lecavalier et al. Chem. Commun., 2013, 49, 11629-11631. DOI: 10.1039/C3CC46209A 

For our J-type HPGe detector with 15% relative effeciency 40K background net count rate is about 0.002 cps (the crystal is in the shade of the shield!); in same place,  45% detector of vertical cryostat model (shield wit the hole in the bottom!) the background is 0.03 cps...

You can find some information at:

Actually it is 2*N*e. Of course the signal you see depends on which charge you collect. If you only collect electrons you will see N*e, even though 2*N*e was produced.

An interesting example of this is the following.

While characterizing Silicon Photomultipliers (SiPM) I measured the photon detection efficiency (PDE). The canonical method, used by everyone till that moment, was to illuminate the photosensor with a monochromatic light source, inside an integrating sphere where a calibrated photodiode is installed. By measuring the photocurrent (after subtracting the dark noise current) and normalizing to the calibrated diode one gets the PDE. This is wrong, for two reasons.

1) With this procedure one includes also the cross-talk in the SiPM.

2) The overall photocurrent is due to electrons AND holes.

I employed a new method, i.e. by counting the single photons with the SiPM and, on top of a better control of the cross-talk, I got the expected result for the PDE (1/2 of what measured with the photocurrent).

The problem is electronic. The first places to look are the cables and connectors. Next is the preamp. Do you have any diagnostic equipment? A pulser and oscilloscope would be useful.

Humidity is a clear indication of an electrostatic problem. Check for proper grounds.

The maximum size for commercial use is 7x7 inches...

Assuming that the proper energy & geometry calibrations were performed for both methods & an adequate sample sizes & count times were used, did you allow for proper ingrowth prior to counting via gamma spec? I suggest waiting for at least 3 weeks after sealing the Marinelli beaker before gamma counting so that the Pb/Bi-214 daughters are in equilibrium with the Ra-226.

If you waited for ingrowth, then I would review all the calibrations-

It is easier to correct for attenuation if the moisture is removed.

Radionuclide concentration is usually for dry weight of soil/

The UNSEAR report

The best place to start in terms of background theory and technical references would be "Radiation Detection and Measurement" by Glenn Knoll.

The 1332keV 60Co gamma ray is conventionally used to give relative efficiency values for detectors, Ge detectors in particular, with the efficiency given relative to a 3x3" NaI(Tl) detector with the source at 25cm. Of course, that only gives efficiency for a single energy and geometry. Which will not be particularly useful unless you are going to be measuring the activity of point-like 60Co sources.

To produce an energy efficiency curve for a detector a wider range of emission energies is needed, which will require sources other than 60Co. Your calibration will also need to be correct for the measurement geometry - so, if you are measuring samples placed in close proximity to your detector you will need calibration materials which emit energies similar to (preferably the same as) those you will be measuring, in a matrix with similar attenuation coefficients to your samples, and with the activity uniformly dispersed throughout a container identical to those used for your samples. If you are using the detector for remote measurements then measurements could be made by moving the source to create a pseudo-distributed source that would account for air attenuation and detector geometric effects.

The options for how you would use a source to calibrate a detector are as diverse as the measurements you are going to be making with that detector. To narrow things down some indication of what you are going to use the detector for would be needed.

I agree with the Radu's answer , furthermore we should consider the effect of the constant temperature not only on the NaI detector but also on the nuclear electronics which connected with the detector, such as the preamp. amplifier ADC or multichannel analyzer , that they all contribute to the stability of the spectra and reduce the shift in peak positions, specially with long time measurments

Is necessary to write a code to simulate the decay scheme of multiple emitters. In the literature we can find some examples

(Laborie et al. 2000; Dias et al. 2002; Johnston et al. 2006)

Dias, M.S., Takeda, M.N. & Koskinas, M.F., 2002. Applied Radiation and Isotopes, 56(1-2), pp.105–109.

Johnston, P.N., Hult, M. & Gasparro, J., 2006. Applied radiation and isotopes, 64(10-11), pp.1323–1328.

Laborie, J.M. et al., 2000. Applied Radiation and Isotopes, 53(1-2), pp.57–62.

According to my experience, the Pa-234m is obtained without difficulty in a gamma spectrum of soil sample through the 1001 keV emission.