NatPy 0.0.5

Convert the units of particle physics quantities.

NatPy

Convert the units of particle physics quantities

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Packages needed:

• astropy
• numpy

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Basic Usage

Code levarages astropy.units.core.Unit and astropy.units.quantity.Quantity objects.

1. Run import natpy.

2. Access physical constants with symbol within const:

   import natpy as nat
   
   >>> nat.const.c
   <class 'astropy.constants.codata2018.CODATA2018'> name='Speed of light in vacuum' value=299792458.0 uncertainty=0.0 unit='m / s' reference='CODATA 2018'>
   
   
   >>> nat.const.hbar
   <class 'astropy.constants.codata2018.CODATA2018'> name='Reduced Planck constant' value=1.0545718176461565e-34 uncertainty=0.0 unit='J s' reference='CODATA 2018'>
   
   

3. Access units with symbol. Combine with values or numpy objects to form quantities:

   >>> nat.m
   Unit("m")
   
   >>> nat.m / nat.s
   Unit("m / s")
   
   >>> 500 * nat.MeV
   <Quantity 500. MeV>
   

4. Specify base of natural units with natpy.set_active_units(). Pass a string corresponding to a list of default natural units, or a list of physical constants to set your own. The list of default bases is found in natpy/default_values.py.

5. Run natpy.convert() to convert between units, including necessary factors of natural units. Pass just unit objects to obtain conversion factors. Pass quantity objects to perform conversions. E.g.

   import natpy as nat
   
   # kg to keV
   >>> nat.convert(nat.kg, nat.keV)
   5.6173581670146864e+32
   
   # Electron mass
   >>> me = nat.convert(9.11e-31 * nat.kg, nat.keV)
   >>> me
   <Quantity 511.74132902 keV>
   
   # Energy of electron with momentum of 1 MeV 
   >>> p = 1 * nat.MeV
   >>> E = np.sqrt(p**2 + me**2)
   
   # Convert to SI units
   >>> nat.convert(E, nat.J)
   <Quantity 1.79926309e-13 J>
   

Note: Summing quanties requires conventionally equivalent units.

6. natpy.convert() may also be accessed a method for unit or quantity objects.

   import natpy as nat
   
   >>> nat.GeV.convert( nat.fm**(-1) )
   5.067730716156395
   
   >>> (1 * nat.GeV).convert( nat.fm**(-1) ) 
   <Quantity 5.06773072 1 / fm>
   

7. See tests/convert_test.py for more examples.