Libraries for AB-22PT data analysis
To analyse a rate measurement in file r1006_06.dat
, you need to import the rate
module:
>>> from lib22pt.rate import *
load the file using class Rate
:
>>> R = MultiRate("r1006_06.dat")
Assuming that you want to fit a decay curve, use the fit_decay
method to do the fit:
>>> param, pval, fitresult = R.fit_decay()
The method returns the fit parameters stored in param
, the fit p-value (goodness of fit) in pval
, and the lmfit MinimizerResult
object in fitresult. The fit has two parameters - initial number N0
and decay rate r
. The fitted parameter values and estimated errors can be printed as
>>> param.pretty_print()
Name Value Min Max Stderr Vary Expr Brute_Step
N0 142.2 -inf inf 2.326 True None None
r 4.522 -inf inf 0.2545 True None None
and the values can be extracted as
>>> print("r = (%.4g +/- %.2g) s^-1" % (param["r"].value, param["r"].stderr))
r = (21.05 +/- 0.45) s^-1
The fitted rate must be divided by the reactant number density to obtain the reaction rate coefficient. It can be obtained from the measured pressure in the chamber Paml22PT
, the trap temperature temp
and the gas-specific calibration factor f_22PT
using the function concentration
from the rate
module. Assuming a reaction with H2 and the following experimental parameters:
T22 = 314. # K
Paml_H2 = 1.4e-8 # Pa
Paml_H2_SIS = 0. # Pa
f_H2_SIS = 38 # calibration from 2015-03-24
the number density is
>>> from lib22pt.util import concentration
>>> n_H2 = concentration(T22, Paml_H2, Paml_H2_SIS, f_H2_SIS)
>>> print("%.3g cm^-3" % n_H2)
1.26e+10 cm^-3
and the rate coefficient is:
>>> k, k_err = param["r"].value/n_H2, param["r"].stderr/n_H2
>>> print("k = (%.4g +/- %.2g) cm^3 s^-1" % (k, k_err))
k = (1.676e-09 +/- 3.6e-11) cm^3 s^-1
The recommended way to make "self-contained" data analysis folders is to copy the lib22pt folder into working directory.
Regular installation:
python3 setup.py install
To install for development:
python3 setup.py develop
To uninstall:
pip3 uninstall lib22pt
Run tests:
python3 setup.py test