Rachel simulated yield output

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(added link to page on normalizations)
(→Accuracy checking)
 
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''This page stub will be updated when a new version of Rachel is released.''
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''This page uses the output of Rachel version 1, which is more intuitive than that of the beta versions.''
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The output to the terminal following a "simulated yields" calculation will be similar to the following until the next release version where the formatting will be improved.
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The output to the terminal from a "simulated yields" calculation has the following format:
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The simulation output now uses the standard definition of efficiency, and the default efficiency curve for any detector can be adjusted by the user.  The user will find prompts for the details of the planned beam run, and estimated absolute measured counts will be calculated and displayed. The display format looks like the following:
<pre>
<pre>
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Experiment 1 Detector  4
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Experiment 1
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                                      Raw                Gamma        Sim.    "Measured"   
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Target excitation by Z,A = 54,136 at 517 MeV. Mean scattering angle = 45.0 deg.
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Band       Spin   Band   Spin     Counts       Error   E(keV)       eps      Counts       Error     
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Detector 1
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--------------------------------------------------------------------------------------------------------
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Single crystal at theta, phi = 45.0, 45.0 deg. Solid angle = 0.06 sr.
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    gsb     6.0     gsb     4.0   32055690        5662    325.6        0.251    127940090      6397044
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This simulation does not include random gaussian scatter. Counts represent the cross sections calculated by Gosia.     
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    gsb     4.0    gsb     2.0   27961778        5288    213.5        0.204    137318753     6865987
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      Transition            |  Gammas incident      |                    Fraction of |        Observed Counts       
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    gsb    2.0    gsb    0.0   2352850        1534     93.3       0.065     36044668     1802387
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                              |  on Ge detectors      | Gamma               Incident    |                               
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Initial         Final        |                      | Energy **Detector  Gammas      |                               
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    Band Spin     Band Spin   | Counts    *Error      | (keV)   Efficiency  Detected    | Rate(Hz)  Counts ***Error     
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-------------------------------------------------------------------------------------------------------------------------
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    gsb 1.5      gsb  0.5     4.662e+06  2.332e+05    100.0 0.00049    0.09962      1.075e+00  4.644e+05  6.815e+02
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    gsb 2.5      gsb  0.5     1.570e+07  7.848e+05     200.0 0.00179    0.36853      1.339e+01  5.784e+06  2.405e+03
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       a  2.5     gsb 0.5     1.079e+04  5.647e+02    250.0 0.00189     0.38907      9.719e-03  4.199e+03  6.480e+01
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      a  2.5      gsb 1.5     9.816e+02  7.705e+01    150.0 0.00135     0.27823      6.322e-04  2.731e+02  1.653e+01
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       a  2.5        b  3.5     4.689e+05  2.376e+04     75.0  0.00015    0.0312        3.387e-02  1.463e+04  1.210e+02
</pre>
</pre>
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Three columns have ambiguous names:
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The "Observed Counts" are calculated using the efficiency curve from the detector library or a detector created by the user.  The "Detector Efficiency" <math>\epsilon</math> is the usual definition.  Possion counting errors are based on the observed counts, while additional error on the ''total'' efficiency-corrected counts may be added by the user.
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===Accuracy checking===
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The predicted absolute counts (cross sections) for p-<math>\gamma</math> events were checked against perturbation calculations for weakly-coupled two-state systems where the perturbation method is valid.  Both the total count rates and solid angle factors have been re-checked in version 2.0.8.beta and agree with the perturbation calculations where they are applicable.  Many tests of fits to simulated yield data without the optional random error scatter resulted in <math>\chi^2</math> values very close to zero, as expected.
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* The "Measured Counts" column gives the true particle-gamma count emitted into the solid angles of the particle and Ge detectors.  This is equivalent to the total counts for the beam run if the detectors were blackbodies (had 100% efficiency), or if the raw counts were corrected for the absolute p-gamma efficiency.
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The ''intrinsic'' efficiency has been estimated more accurately in version 2.0.8.beta.  This will make a noticeable change in the "Raw counts" column.
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* The "Raw Counts" column is only used in this output and is not passed to Gosia.  The raw counts are the estimated p-gamma counts in the raw data, assuming an approximate absolute efficiency for Gammasphere.   
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* The "Sim. eps" column gives the assumed absolute efficiency <math>(\epsilon_{abs})</math> of the Ge detector used to calculate the value in the "Raw counts" column.
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Note that the "Measured Counts" are not sent to Gosia as they appear in the table. 
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===Simulated data passed to Gosia===
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Before the measured counts are sent to Gosia they are divided by the solid angle of each Ge detector to match Gosia's calculation of yield per unit solid angle.  (This is true in Rachel versions >= 2.0.7.beta; in earlier versions this solid angle factor was neglected.)  All yields sent to Gosia are then multiplied by <math>4\pi</math> so that weak transitions have counts >=1.  This overall multiplicative constant of <math>4\pi</math> has no effect on fitting.  Refer to the page [[Normalization_of_yield_data | Normalization of yield data]] for more detail.
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Note that Rachel operates Gosia such that efficiency-corrected "incident gamma" counts are passed to Gosia, but first they are divided by the solid angle of each Ge detector to match Gosia's calculation of yield per unit solid angle.  (This is true in Rachel versions >= 2.0.7.beta; in earlier versions this solid angle factor was neglected, which usually did not result in accuracy errors.)  All yields sent to Gosia are then multiplied by <math>4\pi</math> so that weak transitions have counts >=1.  This overall multiplicative constant of <math>4\pi</math> has no effect on fitting.  Refer to the page [[Normalization_of_yield_data | Normalization of yield data]] for more detail.

Latest revision as of 16:02, 28 January 2012

Retrieved from "https://www-user.pas.rochester.edu/~gosia/mediawiki/index.php/Rachel_simulated_yield_output"
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