def from_string(text, xray_database: TransitionDatabase):
"""
Returns a wavelength parsed from a text in units of Angstrom
:param text:
:param xray_database:
:return:
"""
if any([emisson_line in text
for emisson_line in EMISSON_LINES.keys()]):
for emisson_line in EMISSON_LINES.keys():
if not emisson_line in text:
continue
element = text.replace(emisson_line, '').strip()
transitions = xray_database.get_all_transitions(
element, EMISSON_LINES[emisson_line])
if len(transitions) != 1:
raise WavelengthError(
f"Unknown transition line for '{text}'")
# transition db returns in eV, xray-wavelength expects keV
return xray_wavelength(
transitions[EMISSON_LINES[emisson_line]]['experimental'] *
1e-3)
try:
if 'AA' in text or 'Ang' in text:
wavelength = float(text.replace('AA', '').replace('Ang', ''))
elif 'eV' in text:
wavelength = SI.extract_number(text, 'eV')
else:
# Now we assume there is no unit, which means it should be Angstrom
wavelength = float(text)
except ValueError:
raise WavelengthError(
f"Input '{text}' could not be identified as an wavelength")
if wavelength <= 0:
raise WavelengthError("Wavelength has to be positive")
return wavelength
def attenuation_length(compound,
density=None,
natural_density=None,
energy=None,
wavelength=None):
"""
Calculates the attenuation length for a compound
Transmisison if then exp(-thickness/attenuation_length)
:Parameters:
*compound* : Formula initializer
Chemical formula.
*density* : float | |g/cm^3|
Mass density of the compound, or None for default.
*natural_density* : float | |g/cm^3|
Mass density of the compound at naturally occurring isotope abundance.
*wavelength* : float or vector | |Ang|
Wavelength of the X-ray.
*energy* : float or vector | keV
Energy of the X-ray, if *wavelength* is not specified.
:Returns:
*attenuation_length* : vector | |m|
as function of (energy)
:Notes:
against http://henke.lbl.gov/optical_constants/
"""
if energy is not None: wavelength = xray_wavelength(energy)
assert wavelength is not None, "scattering calculation needs energy or wavelength"
if (numpy.isscalar(wavelength)): wavelength = numpy.array([wavelength])
n = index_of_refraction(compound=compound,
density=density,
natural_density=natural_density,
wavelength=wavelength)
attenuation_length = (wavelength * 1e-10) / (4 * numpy.pi * numpy.imag(n))
return numpy.abs(attenuation_length)
def xafs_sample_prep_get_abslen(request):
"""
Computes the relevant x-ray absorption data.
POSTDATA:
chem: Element chemical formula.
ephot: Photon energy (incoming) in keV.
dens: Compound density in g/cc
bn: Boron Nitride dilution fraction (between 0-1)
RETURNS:
X-ray data as an HTTPresponse string.
"""
if request.method == "POST":
res = "<table class='table table-bordered'>"
try:
#Get POSTDATA
chem = str(request.POST['chem'])
ephot = float(request.POST['ephot'])
dens = float(request.POST['dens'])
bn = float(request.POST['bn'])
except:
res = "Input format error! Please fix and retry."
return HttpResponse(res)
#Parse formula
form = formula(chem)
res += "<tr><td>Compound:</td><td>" + chem + "</td></tr>"
#Compute molecular mass
mass = 0.0
for elem in form.atoms:
mass += form.atoms[elem]*elem.mass
res += "<tr><td>Molecular Mass:</td><td>" + str(round(mass,2)) + " g/mol </td></tr>"
#Compute total mu
mu = 0.0
r_e = 2.8179403E-13 #cm
N_a = 6.02214E23
for elem in form.atoms:
frac = (form.atoms[elem]*elem.mass) / mass
xr = xsf.Xray(elem)
xsec = 2*r_e*xsf.xray_wavelength(ephot)*1E-8*xr.scattering_factors(energy=ephot)[1]*(N_a/elem.mass)
mu += frac * xsec
#Perform dilution with BN if needed
if str(bn) != "" and 0 < bn < 1:
bn_mass = B.mass + N.mass
bn_dens = 2.29 #source: Sigma-Aldrich, BN powder ~1 micron, 98%
frac_b = B.mass / bn_mass
frac_n = N.mass / bn_mass
dens = (1 - bn) * dens + bn * bn_dens
xr_B = xsf.Xray(B)
xsec_B = 2*r_e*xsf.xray_wavelength(ephot)*1E-8*xr_B.scattering_factors(energy=ephot)[1]*(N_a/B.mass)
xr_N = xsf.Xray(N)
xsec_N = 2*r_e*xsf.xray_wavelength(ephot)*1E-8*xr_N.scattering_factors(energy=ephot)[1]*(N_a/N.mass)
mu_bn = frac_b * xsec_B + frac_n * xsec_N
mu = (1 - bn) * mu + bn * mu_bn
res += "<tr><td>BN Dilution Fraction:</td><td>" + str(bn) + "</td></tr>"
mu *= dens
res += "<tr><td>Linear Absorption Coefficient:</td><td>" + str(round(mu,2)) + " 1/cm </td></tr>"
#Compute absorption length
abs_length= round((1/mu) * 10000, 2) #microns
res += "<tr><td>Total X-ray Absorption Length:</td><td>" + str(round(abs_length,2)) + " microns </td></tr>"
#Compute approx. total mass assuming 0.65 cm radius for pellet (standard size for Pike brand pellet press)
total_mass = round(dens * (0.65**2) * 3.14159 * (abs_length/10000) * 1000, 2)
res += "<tr><td>Pellet Mass (13mm diameter):</td><td>" + str(round(total_mass,2)) + " mg</td></tr>"
res += "</table>"
return HttpResponse(res)
else:
return HttpResponse("POSTdata must be used!")
def cgi_call():
form = cgi.FieldStorage()
#print >>sys.stderr, form
#print >>sys.stderr, "sample",form.getfirst('sample')
#print >>sys.stderr, "mass",form.getfirst('mass')
# Parse inputs
errors = {};
calculate = form.getfirst('calculate','all')
if calculate not in ('scattering','activation','all'):
errors['calculate'] = "calculate should be one of 'scattering', 'activation' or 'all'"
try: chem = formula(form.getfirst('sample'))
except: errors['sample'] = error()
try: fluence = float(form.getfirst('flux',100000))
except: errors['flux'] = error()
try: fast_ratio = float(form.getfirst('fast','0'))
except: errors['fast'] = error()
try: Cd_ratio = float(form.getfirst('Cd','0'))
except: errors['Cd'] = error()
try: exposure = parse_hours(form.getfirst('exposure','1'))
except: errors['exposure'] = error()
try:
mass_str = form.getfirst('mass','1')
if mass_str.endswith('kg'):
mass = 1000*float(mass_str[:-2])
elif mass_str.endswith('mg'):
mass = 0.001*float(mass_str[:-2])
elif mass_str.endswith('ug'):
mass = 1e-6*float(mass_str[:-2])
elif mass_str.endswith('g'):
mass = float(mass_str[:-1])
else:
mass = float(mass_str)
except: errors['mass'] = error()
try: density_type,density_value = parse_density(form.getfirst('density','0'))
except: errors['density'] = error()
try:
#print >>sys.stderr,form.getlist('rest[]')
rest_times = [parse_rest(v) for v in form.getlist('rest[]')]
if not rest_times: rest_times = [0,1,24,360]
except: errors['rest'] = error()
try: decay_level = float(form.getfirst('decay','0.001'))
except: errors['decay'] = error()
try: thickness = float(form.getfirst('thickness', '1'))
except: errors['thickness'] = error()
try:
wavelength_str = form.getfirst('wavelength','1').strip()
if wavelength_str.endswith('meV'):
wavelength = nsf.neutron_wavelength(float(wavelength_str[:-3]))
elif wavelength_str.endswith('m/s'):
wavelength = nsf.neutron_wavelength_from_velocity(float(wavelength_str[:-3]))
elif wavelength_str.endswith('Ang'):
wavelength = float(wavelength_str[:-3])
else:
wavelength = float(wavelength_str)
#print >>sys.stderr,wavelength_str
except: errors['wavelength'] = error()
try:
xray_source = form.getfirst('xray','Cu Ka').strip()
if xray_source.endswith('Ka'):
xray_wavelength = elements.symbol(xray_source[:-2].strip()).K_alpha
elif xray_source.endswith('keV'):
xray_wavelength = xsf.xray_wavelength(float(xray_source[:-3]))
elif xray_source.endswith('Ang'):
xray_wavelength = float(xray_source[:-3])
elif xray_source[0].isalpha():
xray_wavelength = elements.symbol(xray_source).K_alpha
else:
xray_wavelength = float(xray_source)
#print >>sys.stderr,"xray",xray_source,xray_wavelength
except: errors['xray'] = error()
try:
abundance_source = form.getfirst('abundance','IAEA')
if abundance_source == "NIST":
abundance = activation.NIST2001_isotopic_abundance
elif abundance_source == "IAEA":
abundance = activation.IAEA1987_isotopic_abundance
else:
raise ValueError("abundance should be NIST or IAEA")
except: errors['abundance'] = error()
if errors: return {'success':False, 'error':'invalid request', 'detail':errors}
# Fill in defaults
#print >>sys.stderr,density_type,density_value,chem.density
if density_type == 'default' or density_value == 0:
# default to a density of 1
if chem.density is None: chem.density = 1
elif density_type == 'volume':
chem.density = chem.molecular_mass/density_value
elif density_type == 'natural':
# if density is given, assume it is for natural abundance
chem.natural_density = density_value
elif density_type == 'isotope':
chem.density = density_value
else:
raise ValueError("unknown density type %r"%density_type)
result = {'success': True}
result['sample'] = {
'formula': str(chem),
'mass': mass,
'density': chem.density,
'thickness': thickness,
'natural_density': chem.natural_density,
}
# Run calculations
if calculate in ('activation', 'all'):
try:
env = activation.ActivationEnvironment(fluence=fluence,fast_ratio=fast_ratio, Cd_ratio=Cd_ratio)
sample = activation.Sample(chem, mass=mass)
sample.calculate_activation(env,exposure=exposure,rest_times=rest_times,abundance=abundance)
decay_time = sample.decay_time(decay_level)
total = [0]*len(sample.rest_times)
rows = []
for el,activity_el in activation.sorted_activity(sample.activity.items()):
total = [t+a for t,a in zip(total,activity_el)]
rows.append({'isotope':el.isotope,'reaction':el.reaction,'product':el.daughter,
'halflife':el.Thalf_str,'comments':el.comments,'levels':activity_el})
result['activation'] = {
'flux': fluence,
'fast': fast_ratio,
'Cd': Cd_ratio,
'exposure': exposure,
'rest': rest_times,
'activity': rows,
'total': total,
'decay_level': decay_level,
'decay_time': decay_time,
}
#print >>sys.stderr,result
except:
result['activation'] = {"error": error()}
#nsf_sears.replace_neutron_data()
if calculate in ('scattering', 'all'):
try:
sld,xs,penetration = neutron_scattering(chem, wavelength=wavelength)
result['scattering'] = {
'neutron': {
'wavelength': wavelength,
'energy': nsf.neutron_energy(wavelength),
'velocity': nsf.VELOCITY_FACTOR/wavelength,
},
'xs': {'coh': xs[0], 'abs': xs[1], 'incoh': xs[2]},
'sld': {'real': sld[0], 'imag': sld[1], 'incoh': sld[2]},
'penetration': penetration,
'transmission': 100*exp(-thickness/penetration),
}
except:
missing = [str(el) for el in chem.atoms if not el.neutron.has_sld()]
if any(missing):
msg = "missing neutron cross sections for "+", ".join(missing)
else:
msg = error()
result['scattering'] = {'error': msg }
try:
xsld = xray_sld(chem, wavelength=xray_wavelength)
result['xray_scattering'] = {
'xray': {
'wavelength': xray_wavelength,
'energy': xsf.xray_energy(xray_wavelength),
},
'sld': {'real': xsld[0], 'imag': xsld[1]},
}
except:
result['xray_scattering'] = {'error': error()}
return result
