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This note describes the python modules which help to access calibrated geometry parameters for CSPAD2x2.

Calibration types

Current total list of calibration types for CSPAD2x2 is shown in the table:

Type

Shape

Description

center

(3, 2)

x, y, z coordinates of the two 2x1 centers

tilt

(2,)

tilt angle of the two 2x1s assuming rotation angle = 180 degrees

beam_vector

(3,)

The same as for CSPAD

filter

(3,)

The same as for CSPAD

common_mode

(3,)

The same as for CSPAD

pedestals

(185, 388, 2)

The same as for CSPAD

pixel_status

(185, 388, 2)

The same as for CSPAD

Two of them, center and tilt, are used to describe precise pixel geometry in the detector. The beam_vector is intended (but not used yet and need to be elaborated) to describe the detector position w.r.t. IP. Other types, filter, common_mode, pedestals, and pixel_status, have the same meaning as for CSPAD detector and are used for intensity correction, that is beyond the scope of this note.

Code location

All modules discussed in this note belong to the package PyCSPadImage of psana
release, beginning from ana-0.9.8. This package contain modules for CSPAD and CSPAD2x2
detectors. Module with name pattern CSPAD2x2*.py are intended for CSPAD2x2.
Their functionality is explained in the table:

Class name

Functionality

CSPAD2x2CalibPars.py

Provides access to the calibration parameters through the DB

CSPAD2x2CalibParsDefault.py

Sets default values for all calibration types

CSPAD2x2Examples.py

Example of how to get calibrated data, get image, and plot it

CSPAD2x2PixCoords.py

Provides access to the pixel coordinate arrays

PixCoords2x1.py

Provides access to the pixel coordinate arrays for 2x1 sensor

GlobalGraphics.py

A set of simple graphical methods based on matplotlib

HDF5Methods.py

A set of methods for interaction with hdf5 files

GlobalMethods.py

A set of useful global methods

Program interface

Import

The modules discussed in this note can be imported as:

import PyCSPadImage.CSPAD2x2PixCoords as pixcoor
import PyCSPadImage.CSPAD2x2CalibPars as calpars

In example we also import a couple of useful modules:

import PyCSPadImage.HDF5Methods       as hm 
import PyCSPadImage.GlobalGraphics    as gg

Instantiate calibration object

The object of the class CSPAD2x2CalibPars may be instantiated by a few different ways, as explained below.

Regular constructor

For regular instantiation of the calibration object, the class CSPAD2x2CalibPars constructor expects at least two (named) parameters,

  • path - the string path to the directory with calibration types, and
  • run - integer run number.
    Third parameter list_of_clib_types is used for run-time optimization; if it is missing, all parameters will be loaded, that takes more time and memory. 
        # Official path:
    path = '/reg/d/psdm/mec/mec73313/calib/CsPad2x2::CalibV1/MecTargetChamber.0:Cspad2x2.1/
    # or local:
    # path = '/reg/neh/home1/dubrovin/LCLS/CSPad2x2Alignment/calib-cspad2x2-01-2013-02-13/'
list_of_clib_types = ['center', 'tilt', 'pedestals']
    calib = calpars.CSPAD2x2CalibPars(path, run, list_of_clib_types)

Default constructor

Calibration object can be instantiated without parameters;

    calib = calpars.CSPAD2x2CalibPars()

Default values of all parameters will be used in this case, which allows to run code without any crash, but does not provide correct geometry. Necessary parameters may be provided later by the methods:

    calib.setCalibParsForPath (run, path)

or

    run      = 123, 
    calibdir = '/reg/d/psdm/mec/mec73313/calib',
    group    = 'CsPad2x2::CalibV1',
    source   = 'MecTargetChamber.0:Cspad2x2.1'

    calib.setCalibPars (run, calibdir, group, source) :

Update run number

If the path to calibration types is already instantiated, the run number can be changed in the process of analysis by the call like

    run=234 # actual run number should be provided...
    calib.setRun (run)

Get pixel coordinates

In order to get the CSPAD2x2 geometry calibrated parameters, the coord object of the class CSPAD2x2PixCoords needs to be instatiated, using calibration parameters loaded in the calib object. Then the X and Y pixel coordinate (numpy) arrays of the data-like shape (185, 388, 2) can be obtained through the method get_cspad2x2_pix_coordinate_arrays_pix(),

    coord = pixcoor.CSPAD2x2PixCoords(calib)
    X,Y = coord.get_cspad2x2_pix_coordinate_arrays_pix()

Get array of calibration parameters

Method calib.getCalibPars(type, run) allows to get array of calibration parameters for specific type and run number, for example

    peds_arr = calib.getCalibPars('pedestals',123)

returns the pedestals (numpy) array with data-like shape (185, 388, 2).

Conversion between (185, 388, 2) and (2, 185, 388) shapes

Module CSPAD2x2CalibPars.py contains a couple of global methods which convert the array shape forth and back between (185, 388, 2) and (2, 185, 388);

arrTwo2x1 = calpars.data2x2ToTwo2x1(arr2x2)    # converts (185, 388, 2) to (2, 185, 388)
arr2x2    = calpars.two2x1ToData2x2(arrTwo2x1) # converts (2, 185, 388) to (185, 388, 2)

Get CSPAD2x2 data array from hdf5 file

import HDF5Methods as hm 
    fname  = '/reg/neh/home1/dubrovin/LCLS/HDF5Analysis-v01/PyCSPadImage/src/mec73313-r0180.h5
    dsname = '/Configure:0000/Run:0000/CalibCycle:0000/CsPad2x2::ElementV1/MecTargetChamber.0:Cspad2x2.1/data'
    data_arr = hm.getDataSetForOneEvent(fname, dsname, event=0)

Image from pixel coordinate and intensity arrays

Depending on experimental requirements, there may be different methods of how to generate image. For example we use a simple 2-d histogram technique.
The CSPAD2x2 image can be obtained from the pixel coordinate and intensity arrays (of the same shape) by call:
img2d = gg.getImageFromIndexArrays(X,Y,arr)

Plot image and its spectrum

import GlobalGraphics as gg
    my_range = None
    my_range = (-10,40)
    gg.plotImageLarge(img2d, amp_range=my_range)        
    gg.plotSpectrum(img2d, amp_range=my_range)
    gg.show()

Code example

Essential code of the module CSPAD2x2Examples.py:

import sys
import numpy as np

import PyCSPadImage.CSPAD2x2PixCoords as pixcoor
import PyCSPadImage.CSPAD2x2CalibPars as calpars

import PyCSPadImage.HDF5Methods       as hm 
import PyCSPadImage.GlobalGraphics    as gg
#------------------------------

def test_cspad2x2_calib_geometry() :
    """Test method, demonstrates how to work with CSPAD2x2CalibPars and CSPAD2x2PixCoords modules
    """    
    #======= Define input parameters
    Ndet = 5
    run  = 180
    path = '/reg/d/psdm/mec/mec73313/calib/CsPad2x2::CalibV1/MecTargetChamber.0:Cspad2x2.%1d/' % Ndet
    #path = '/reg/neh/home1/dubrovin/LCLS/CSPad2x2Alignment/calib-cspad2x2-0%1d-2013-02-13/' % Ndet
    #fname  = '/reg/d/psdm/mec/mec73313/hdf5/mec73313-r%04d.h5' % run
    fname  = '/reg/neh/home1/dubrovin/LCLS/HDF5Analysis-v01/PyCSPadImage/src/mec73313-r%04d.h5' % run
    dsname = '/Configure:0000/Run:0000/CalibCycle:0000/CsPad2x2::ElementV1/MecTargetChamber.0:Cspad2x2.%1d/data' % Ndet
    list_of_clib_types = ['center', 'tilt', 'pedestals']

    #======= Get calibration object
    calib = calpars.CSPAD2x2CalibPars(path, run, list_of_clib_types)

    #======= Get CSPAD2x2 pixel coordinate arrays, shaped as (2, 185, 388)
    coord = pixcoor.CSPAD2x2PixCoords(calib)
    X,Y = coord.get_cspad2x2_pix_coordinate_arrays_pix()

    #======= Get CSPAD2x2 pedestals array, shaped as (185, 388, 2)
    peds_arr = calib.getCalibPars('pedestals')

    #======= Get data array from hdf5 dataset, shaped as (185, 388, 2)
    data_arr = hm.getDataSetForOneEvent(fname, dsname, event=0) - peds_arr
    
    #======= Convert shape from (185, 388, 2) to (2, 185, 388)    
    ord_arr  = calpars.data2x2ToTwo2x1(data_arr)

    #======= Compose and plot CSPAD2x2 image from coordinate and intensity arrays
    img2d = gg.getImageFromIndexArrays(X,Y,ord_arr)

    #======= Print for test purpose 
    calib.printCalibParsStatus()
    #print 'pedestals:\n', calib.getCalibPars('pedestals')
    print 'center:\n',    calib.getCalibPars('center')
    print 'tilt:\n',      calib.getCalibPars('tilt')
    print 'peds_arr.shape:', peds_arr.shape  # = (185, 388, 2)  
    print 'Get data array from file: ' + fname
    print 'data_arr.shape:', data_arr.shape
    print 'ord_arr.shape:', ord_arr.shape
    print 'img2d.shape:', img2d.shape

    #======= Plot image and spectrum
    my_range = (-10,40) # None
    gg.plotImageLarge(img2d, amp_range=my_range)        
    gg.plotSpectrum(img2d, amp_range=my_range)
    gg.show()

#------------------------------
 if __name__ == "__main__" :
    test_cspad2x2_calib_geometry()
    sys.exit ( 'End of test.' )
#------------------------------

This example generates a couple of plots for CSPAD2x2 image and spectrum:

References

CSPad2x2 Alignment
CSPAD Geometry and Alignment

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