### Author:  [@Richard](https://openmc.discourse.group/u/Richard)
#### Post date: [May 31, 2024, 6:42pm UTC](https://openmc.discourse.group/t/cylinder-source-in-fixed-source-mode/4337/1 "2024-05-31T18:42:40Z")
Hello, I am now trying to create multiple cylindrical sources in the mode ‘fixed source’, those sources are are just different in coordinates x,y and the other settings are totatly same. And I met two problems:
Here are my code:
```auto
radius=0.25
r=openmc.stats.PowerLaw(0.0,radius,1.0)
phi=openmc.stats.Uniform(0.0,2*pi)
z=openmc.stats.Uniform(-fuelLength/2,fuelLength/2)
x=[]
y=[]
m=12
for n in range(17-m):
for i in range(5):
for j in range(9-i):
if i==0:
x.append((3 ** 0.5) * m * L2 / 2 + (j - (8 - i) / 2) * L1)
y.append((n - 8 + 0.5 * m) * L2 + (3 ** 0.5) * i * L1 / 2)
else:
x.append((3 ** 0.5) * m * L2 / 2 + (j - (8 - i) / 2) * L1)
y.append((n - 8 + 0.5 * m) * L2 + (3 ** 0.5) * i * L1 / 2)
x.append((3 ** 0.5) * m * L2 / 2 + (j - (8 - i) / 2) * L1)
y.append((n - 8 + 0.5 * m) * L2 - (3 ** 0.5) * i * L1 / 2)
energy_bins = [1.00E-05, 0.625, 100, 1000, 5.00E+03, 10000, 50000, 1.00E+05, 200000, 300000, 4.00E+05,
500000, 600000, 700000, 800000, 900000, 1000000, 2000000, 3000000, 4000000, 5000000,
6000000, 7000000, 8000000, 9000000, 10000000, 20000000]
probability_density = [0.114804354, 0.130632628, 0.073037242, 0.056694686, 0.025809602, 0.06903753,
0.038666972, 0.051744062, 0.041062851, 0.034657177, 0.02416415, 0.027668522,
0.027214132, 0.025025168, 0.021317823, 0.015144402, 0.108801774, 0.059257734,
0.026894671, 0.014246912, 0.007213418, 0.003657553, 0.001703832, 0.00081529,
0.00038822, 0.000339297]
sources=[]
for i in range(len(x)):
source = openmc.Source()
source = openmc.stats.CylindricalIndependent(r, phi, z, origin=(x[i], y[i], 0.0))
source.angle = openmc.stats.Isotropic()
source.energy = openmc.stats.Tabular(energy_bins, probability_density)
sources.append(source)
# Indicate how many particles to run
settings = openmc.Settings()
settings.run_mode = 'fixed source'
settings.batches = 100
settings.inactive = 50
settings.particles = 1000
settings.temperature = {"method":"interpolation","range":(280+273.15,320+273.15),"multipole":True}
settings.source = sources
settings.export_to_xml()
```
Firstly, i dont konw why it made an error as follow:
> Blockquote
> TypeError: Unable to set “source distributions” to \" which is not of type:“SourceBase”
what should i modify my code?
Secondly, for the energy spectrum of my source, I have a series of continuous energy intervals and their probability density:
| energy low [eV] | energy high [eV] | probability\_density |
| --- | --- | --- |
| 1.00E-05 | 0.625 | 0.114804354 |
| 0.625 | 100 | 0.130632628 |
| 100 | 1000 | 0.073037242 |
| 1.00E+03 | 5.00E+03 | 0.056694686 |
| 5000 | 10000 | 0.025809602 |
| 10000 | 50000 | 0.06903753 |
| 5.00E+04 | 1.00E+05 | 0.038666972 |
| 100000 | 200000 | 0.051744062 |
| 200000 | 300000 | 0.041062851 |
| 3.00E+05 | 4.00E+05 | 0.034657177 |
| 400000 | 500000 | 0.02416415 |
| 500000 | 600000 | 0.027668522 |
| 600000 | 700000 | 0.027214132 |
| 700000 | 800000 | 0.025025168 |
| 800000 | 900000 | 0.021317823 |
| 900000 | 1000000 | 0.015144402 |
| 1000000 | 2000000 | 0.108801774 |
| 2000000 | 3000000 | 0.059257734 |
| 3000000 | 4000000 | 0.026894671 |
| 4000000 | 5000000 | 0.014246912 |
| 5000000 | 6000000 | 0.007213418 |
| 6000000 | 7000000 | 0.003657553 |
| 7000000 | 8000000 | 0.001703832 |
| 8000000 | 9000000 | 0.00081529 |
| 9000000 | 10000000 | 0.00038822 |
| 10000000 | 20000000 | 0.000339297 |
I am not sure the setting ‘source.energy’ in my code is correct. If not, how can i do it?
Thanks,
Richard
---
### Author:  [@thilagam](https://openmc.discourse.group/u/thilagam)
#### Post date: [June 3, 2024, 12:26pm UTC](https://openmc.discourse.group/t/cylinder-source-in-fixed-source-mode/4337/2 "2024-06-03T12:26:32Z")
Sir, Have you resolved your issue? I am facing the same problem for defining multiple sources. If possible, kindly guide me.
With thanks & best regards,
L Thilagam
---
### Author:  [@Richard](https://openmc.discourse.group/u/Richard)
#### Post date: [June 4, 2024, 3:38am UTC](https://openmc.discourse.group/t/cylinder-source-in-fixed-source-mode/4337/3 "2024-06-04T03:38:21Z")
For the first problem, that is my mistake. It must be:
```auto
source.space = openmc.stats.CylindricalIndependent(r, phi, z, origin=(x[i], y[i], 0.0))
```
And for the second one, my mentor told me that it should be set up this way:
```auto
energy_bins = [1.00E-05, 0.625, 100, 1000, 5.00E+03, 10000, 50000, 1.00E+05, 200000, 300000, 4.00E+05,
500000, 600000, 700000, 800000, 900000, 1000000, 2000000, 3000000, 4000000, 5000000,
6000000, 7000000, 8000000, 9000000, 10000000, 20000000]
probability_density = [0.114804354, 0.130632628, 0.073037242, 0.056694686, 0.025809602, 0.06903753,
0.038666972, 0.051744062, 0.041062851, 0.034657177, 0.02416415, 0.027668522,
0.027214132, 0.025025168, 0.021317823, 0.015144402, 0.108801774, 0.059257734,
0.026894671, 0.014246912, 0.007213418, 0.003657553, 0.001703832, 0.00081529,
0.00038822, 0.000339297,0]
source.energy = openmc.stats.Tabular(energy_bins, probability_density,'histogram')
```
Hope that helpful for you
---
### Author:  [@ron](https://openmc.discourse.group/u/ron)
#### Post date: [June 5, 2024, 1:32pm UTC](https://openmc.discourse.group/t/cylinder-source-in-fixed-source-mode/4337/4 "2024-06-05T13:32:45Z")
Richard
This worked for me. Note the use of openmc\_source\_plotter to actually view the source configuration and energy.
I left a number of your steps in (as comments) to help clarify the changes that I made.
I did not try to make the input neat or concise, so there may be code that is unneeded or redundant.
I wasn’t sure what you were trying to do with the variables L1 & L2, so I assumed the had something to do with the source length.
Thanks for posting the question. It helped me learn OpenMC a little better.
from math import pi, sin, cos
import numpy as np
import openmc
from openmc\_source\_plotter import plot\_source\_position
radius=0.25
pi=np.pi
fuelLength=10.0
L1=fuelLength/2.5
L2=fuelLength/2.0
source = openmc.IndependentSource()
r=openmc.stats.PowerLaw(0.0,radius,1.0)
phi=openmc.stats.Uniform(0.0,2\*pi)
z=openmc.stats.Uniform(-fuelLength/2,fuelLength/2)
x=
y=
m=12
# for n in range(17-m):
# for i in range(5):
# for j in range(9-i):
# if i==0:
# x.append((3 \*\* 0.5) \* m \* L2 / 2 + (j - (8 - i) / 2) \* L1)
# y.append((n - 8 + 0.5 \* m) \* L2 + (3 \*\* 0.5) \* i \* L1 / 2)
# else:
# x.append((3 \*\* 0.5) \* m \* L2 / 2 + (j - (8 - i) / 2) \* L1)
# y.append((n - 8 + 0.5 \* m) \* L2 + (3 \*\* 0.5) \* i \* L1 / 2)
# x.append((3 \*\* 0.5) \* m \* L2 / 2 + (j - (8 - i) / 2) \* L1)
# y.append((n - 8 + 0.5 \* m) \* L2 - (3 \*\* 0.5) \* i \* L1 / 2)
energy\_bins = [1.00E-05, 0.625, 100, 1000, 5.00E+03, 10000,
50000, 1.00E+05, 200000, 300000, 4.00E+05, 500000,
600000, 700000, 800000, 900000, 1000000, 2000000,
3000000, 4000000, 5000000, 6000000, 7000000, 8000000,
9000000, 10000000, 20000000]
probability\_density = [0.114804354, 0.130632628, 0.073037242, 0.056694686, 0.025809602, 0.06903753,
0.038666972, 0.051744062, 0.041062851, 0.034657177, 0.02416415, 0.027668522,
0.027214132, 0.025025168, 0.021317823, 0.015144402, 0.108801774, 0.059257734,
0.026894671, 0.014246912, 0.007213418, 0.003657553, 0.001703832, 0.00081529,
0.00038822, 0.000339297, 0]
# sources=
# for i in range(len(x)):
# sources = openmc.stats.CylindricalIndependent(r, phi, z, origin=(x[i], y[i], 0.0))
# sources.angle = openmc.stats.Isotropic()
# sources.energy = openmc.stats.Tabular(energy\_bins, probability\_density,‘histogram’)
# sources.append(source)
spatial\_dist = openmc.stats.CylindricalIndependent(r, phi, z)
source.angle = openmc.stats.Isotropic()
source.energy = openmc.stats.Tabular(energy\_bins, probability\_density,‘histogram’)
source.space=spatial\_dist
settings = openmc.Settings()
settings.source = source
settings.export\_to\_xml()
# Indicate how many particles to run
settings = openmc.Settings()
settings.run\_mode = ‘fixed source’
settings.batches = 100
settings.inactive = 50
settings.particles = 1000
settings.temperature = {“method”:“interpolation”,“range”:(280+273.15,320+273.15),“multipole”:True}
settings.source = source
settings.export\_to\_xml()
# plots the particle energy distribution
plot = plot\_source\_position(source)
plot.show()
---
### Author:  [@Richard](https://openmc.discourse.group/u/Richard)
#### Post date: [June 5, 2024, 2:22pm UTC](https://openmc.discourse.group/t/cylinder-source-in-fixed-source-mode/4337/5 "2024-06-05T14:22:12Z")
Thanks for your suggestion. I will check it with openmc\_source\_plotter.
Best regards