Need of doc in TSpectrum:Search

Hello, in the doc of Search mathod of TSpectrum, one can read

The problem is I do not find any information on the Serach method of TSpectrum in the ROOT User Guide. Does it refer to another manual?
So could you clarify that point in the web documentation or add a section in the ROOT User Guide. Quickly, I hust wanted to know what is the “unit” of sigma. I understand that a big sigma corresponds to wide peaks and a small one to narrow peaks. But what does “big” and “small” means? What is the unit of “sigma” (bin, value, …)?
Thanks in advance.

Thread [url= might contain answer to the first question.

You are right, I guess this refers to this document. Maybe the link to this document could be provided directly in the HTML documentation.

I have translated the Spectrum Word document into markown. This allows to have this manual in the ROOT related user’s guides page:
Note that this manual is now available in:

  • pdf (A4 and letter)
  • html
  • epub

Dear Couet,
So, what is sigma?
Is it possible to give this information in this topic, because I see many links and new link inside them and such links do not work or without this information.

what do you mean ? which “sigma” are you talking about ?

In TSpectrum class there is a method

Int_t TSpectrum::SearchHighRes 	( 	Double_t *  	source,
		Double_t *  	destVector,
		Int_t  	ssize,
		Double_t  	sigma,
		Double_t  	threshold,
		bool  	backgroundRemove,
		Int_t  	deconIterations,
		bool  	markov,
		Int_t  	averWindow 

I try to understand what is Double_t sigma.

This documentation is delivered “as it is” . The author of this code and documentation is not available anymore. I am afraid you we cannot give you more details than what is written in this doc or what you can read in the code itself.

Just to clarify:
Do you mean and

  1. M.A. Mariscotti: A method for identification of peaks in the presence of background and its application to spectrum analysis. NIM 50 (1967), 309-320.
  2. M. Morhac;, J. Kliman, V. Matouoek, M. Veselsky, I. Turzo.:Identification of peaks in multidimensional coincidence gamma-ray spectra. NIM, A443 (2000) 108-125.
  3. Z.K. Silagadze, A new algorithm for automatic photopeak searches. NIM A 376 (1996), 451.


Do you have the first article in free access on root cern web cite ?

All what we have is:

Dear Couet,
Thank you for your help!
I will try to find this info in source code.

Hi Vladislav,

The following is written in the middle of section 3.1 of the TSpectrum guide:

…The value in the center of the peak value[i] minus the average value in two symmetrically positioned channels (channels i-3*sigma, i+3*sigma) must be greater than threshold. Otherwise the peak is ignored…

1 Like

Ah good ! So you found it :slight_smile:

Thanks a lot! :+1::+1::+1: