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2025-06-12T12:35:06Z

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WORKING
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Rachel format matrix file

2012-05-03T14:26:24Z

Hayes: Added general format description and format for coupled (dependent) matrix elements

Rachel can import a matrix from a text file. Currently the Rachel format below is the only one supported, but in the future it will be possible to read the level scheme and matrix from a Gosia input file.

The format of the matrix file is shown below by example.

<pre>
g 0.0 g 2.0 E2 0.7 master 0.01 5.
g 2.0 g 2.0 E2 0.1 master -5. 5.
g 2.0 g 4.0 E2 0.5 master 0.01 5.0
g 4.0 g 4.0 E2 0.2 fixed
a 4.0 a 5.0 E2 0.3 master 0.01 10.0
a 4.0 a 5.0 M1 0.4 coupled E2 a 4.0 a 5.0
</pre>

The general format is

<pre>
initial_band_name initial_spin final_band_name final_spin multipole_code value "fixed"
</pre>

(omitting quotation marks) for a fixed-value matrix element (not to be fitted),

<pre>
initial_band_name initial_spin final_band_name final_spin multipole_code value "master" lower_limit upper_limit
</pre>

(omitting quotation marks) for a master matrix element and

<pre>
(same first 6 fields as above) "coupled" master_multipole master_initial_band master_initial_spin master_final_band master_final_spin
</pre>

(omitting quotation marks) for a matrix element coupled to a master matrix element.

The fixed/master/coupled status can be changed later in the GUI.

The matrix element value is in units of powers of e, b and nuclear magnetons.

Gosia errors

2012-03-04T17:52:59Z

Hayes: Created page with "The errors described below are reported in the output file, and/or in the terminal as a Gosia calculation terminates. ==Exceeding the range of conversion coefficients== When us..."

The errors described below are reported in the output file, and/or in the terminal as a Gosia calculation terminates.

==Exceeding the range of conversion coefficients==

When using the built-in internal conversion coefficient calculation function, there may be frequent reports similar to the following.

<pre>
Warning Egamma= 0.8596 exceeds range of conversion coefficients table for shell N7
0.8596 2.174E-03 5.586E-03 1.299E-02 1.212E-02 3.128E-02
</pre>

This does not necessarily indicate an accuracy error in Gosia calculations. The internal conversion coefficients reported after the warnings can be checked for accuracy. Accuracy errors in [[internal_conversion | internal conversion coefficients]] should only be large near K, L,... edges and for very low gamma-ray energies. (reference needed)

Common mistakes

2012-03-03T15:12:38Z

Hayes:

==Too many fit parameters (e.g. forgetting the overall normalization parameter)==

This problem will not cause an error to be reported by Gosia.

If the system is not overdetermined, then fits will not represent a true minimum. With more than a few fit parameters, the system must be very overdetermined using many experiments or scattering angle ranges, etc.

A common mistake is to forget that Gosia must fit the overall normalization of cross section to measured gamma-ray counts. (This effectively includes the total beam dose, detector efficiencies, etc.) If, for example, Gosia is used to try to fit the B(E2) in a two-state calculation, this overall normalization parameter will adjust to allow any B(E2) value at the chi-squared minimum. The fit will converge, and Gosia will not report an error, but the fitted B(E2) will be meaningless.

Using Gosia 2 in two-state systems with measured yields for both the projectile and the target is designed to overcome this problem.

==Insufficient integration accuracy==

This problem will not cause an error to be reported by Gosia.

Gosia does not test that the [[integrated_yields | integrated yields]] (the accurate yields or cross sections integrated over the energy loss in the target and the solid angle of the scattered particle) are converged. Usually, the most sensitive set is the angular meshpoints, but this is not always the case.

===Integration meshpoints===

Gosia does not test convergence for the user's chosen integration meshpoints.

If the integrated yields are not converged, then the predicted cross sections will be inaccurate, and this will also cause an inaccurate fit via the [[corrected_yields | corrected yields]].

There are two ways to test for convergence:

# The Rachel interface chooses sufficient meshpoints in energy and scattering angle for convergence, but possibly more than necessary. Generating an input with Rachel, or running all calculations in Rachel 'should' always give converged calculations. Rachel also has a built-in test, option "ti" in the Tools button menu, that will test the convergence for a choice of meshpoints. However, sometimes Gosia does not have sufficient memory for this test for very large level schemes, and it must be performed with a subset of the bands.

# The only certain test that there are sufficient meshpoints for convergence is to look at the integrated yields (OP,INTI) with an increasing number of meshpoints 'for each experiment'. Once the required meshpoint spacing is found, calculation time can be minimized by choosing the fewest required.

Once the meshpoint requirement has been found, it does not need to be tested again for OP,CORR [[corrected_yields | corrected yields]] or any other function.

===Integration meshpoint subdivisions===

The meshpoint [[integration_subdivisions | subdivisions]] can be tested to see if increasing the number of subdivisions will allow for fewer required meshpoints. Increasing the number of meshpoints significantly increases the calculation time, but increasing the number of subdivisions does not. (It is probably wisest to pick 50 or 100 subdivisions and then test for the required number of meshpoints for convergence.)

===Convergence of the coupled-channels calculations===

In order to ensure convergence in the point cross sections, it is best to prevent Gosia from trying to reduce the step-size used in the collision trajectory. This is done by adding the "INT," control to the CONT section of the input. (Refer to "CONT" in the Gosia manual.) To turn off the step-size reduction, add

<pre>
INT,X.
1, 1000
2, 1000
...
</pre>

where X is the number of experiments in the input, and 1, 2, ... are the experiment numbers 1 through X. The decimal point is required after X.

Rachel 1.0 tutorial videos

2012-01-27T16:51:53Z

Hayes: /* Procedures in the usual order */

These tutorials are listed by procedure, in the typical ordering of procedures. They are all in MP4 format. If they do not play properly, you probably need a new browser plugin for MP4.

Please suggest other topics for tutorial videos through the [http://www-user.pas.rochester.edu/~gosia/phpBB3/ Gosia forum.]

The approximate running time is shown after each link.

===Procedures in the usual order===

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/installation.html Installation] 5 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/read_level_schemes.html Level schemes] 5 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/add_matrix.html Adding the matrix] 5 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/set_fit_parameters.html Setting fit parameters] 4 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/add_experiments.html Adding experiments] 7 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/stopping_power.html Calculating accurate stopping power, exit energy and range] 5 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/define_ge_crystals.html Defining Ge detector types] 4 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/attach_ge_detectors.html Attaching Ge detectors and arrays (laboratory positions)] 4 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/nuclear_data.html Adding nuclear data to a fit] 4 minutes.
Adding previously-measured lifetime or matrix element data is usually vital to finding a unique fit in few-state systems.

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/op_gdet.html Passing germanium types to Gosia] 1 minute. Be sure to do this before the following steps!

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/loading_yield_data.html Loading yield data and passing the data to Gosia] 4 minutes

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/simulation.html Simulating gamma-ray yield data] 4 minutes. This can be used for predicting count rates, testing the ability to fit matrix elements in a planned experiment, etc.

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/integrated_yields.html Calculating gamma-ray yields] 3 minutes. This calculation uses a full integration over the particle detector, Ge detector and energy loss in the target. These are the yields that should be compared to data.

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/corrected_yields.html Calculating "corrected" yields from yield data and the normalization constants.] 3 minutes. This is the first step in fitting matrix elements to experimental data. These two steps should be repeated every time a fit is done.

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/fitting.html Fitting matrix elements to experimental data.] 9 minutes. Be sure to calculate the normalization constants before fitting. This is shown in the corrected yields tutorial.

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/error_calculations.html Diagonal and correlated error calculations.] 4 minutes.

===Other functions===

[http://www.pas.rochester.edu/~hayes/rachel_1_videos/math_interpreter.html Using the math interpreter] 2 minutes

Rachel physical detector files

2011-12-14T17:55:09Z

Hayes: Created page with "Several physical detectors (crystal types, not laboratory positions) can be defined by reading a text file of the following format. (See also the [[Rachel_format_detector_arra..."

Several physical detectors (crystal types, not laboratory positions) can be defined by reading a text file of the following format.

(See also the [[Rachel_format_detector_array_files|physical detector format]] for defining detector positions in the laboratory. This is useful for defining and sharing the definitions of large detector arrays.)

This file can be read by selecting option ip from the Tools button menu.

The user-readable text file format is as follows:

<pre>
somecrystal
description Some type of Ge crystal
distance 20
outer_radius 4
inner_radius .4
length 9

someother
description some other type of Ge crystal
distance 30
outer_radius 3
inner_radius .3
length 10
</pre>