X-ray Capability for Energy
Response
Ludlum already has many capabilities in-house:
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PMT’s and plastic scintillators
Circuit boards (4-layer SMT)
Transformers
Cables and Harnesses
Welding (Alum and Steel)-Robot added 2011
Stamping, Milling, Turning
Die and Mold making
Plastic Injection Molding
Lead Casting
Wire EDM machining
Alpha, Beta, Gamma, and Neutron source calibrations
But not much energy response capability.
Customers sometimes ask difficult questions
about energy response…and not enough
monoenergetic radiation sources with long
half-lives exist to test well. To test both GM
and scintillation detectors, we would need
both uR/hr and mR/hr level sources.
Sometimes, it’s just not good enough to use
supplier or scientific data.
As more sales go international…more people
are starting to realize that there are energy
differences between exposure units and
dose equivalent units. “Energy-flat” in terms
of exposure isn’t the same as “energy-flat” in
terms of dose equivalent.
And more people are asking “Why shouldn’t
the US join the rest of the world in using the
Sievert?”
Sv/R Conversion ISO 4037-1
0.016
0.014
0.012
0.01
0.008
0.006
0.004
0.002
0
0
100
200
300
400
500
600
700
Once the decision to purchase an x-ray
machine was made we needed:
1. A location
2. An appropriate x-ray machine
3. Radiation license and safety
4. Setup and Calibration
• An unused 2nd floor site was chosen…with
six inch concrete floor and plenty of spaceapproximately 40 feet wide by 100 feet long.
When looking at x-ray systems used by other
calibration facilities we found:
NIST: Pantak HF320 system
LANL: Pantak HF320 system
ORNL: Pantak HF320 system
PNNL: Pantak HF320 system
Ludlum decided to get the same system.
• A used (1999) Pantak HF320 system was
purchased, which would give crucial energy
response data in the 20-300 keV region.
• An x-ray technician installed and calibrated
the system onsite, and provide operational
training.
Ludlum RSO performed the license modification:
radiation source and x-ray devices handled
separately.
“X-ray in Use” signs and lights installed.
Door Interlocks installed downstairs-opening door
causes control panel to shut beam off.
Radiological survey done inside on the 1st and 2nd
floors and also outside with beam at full working
power and kVp.
Procedures written for use, log and safety equipment
established.
NIST H-series filters-made with 99%+ pure
materials
Two filter wheels were made, each holding 8
filters. The second wheel hold HVL, used to
verify the correct output spectral energy.
X-ray Calibration
A NIST-traceable PTW ion chamber was used
to establish exposure and dose rates at
approximately 16 feet.
A CdTe isotope identifier (ICS-4000) was used
to qualitatively see the spectra.
H200
70000
60000
50000
40000
H200
30000
20000
10000
1
22
43
64
85
106
127
148
169
190
211
232
253
274
295
316
337
358
379
400
0
Clearly, we had some serious scattering issues…some additional steel
shielding was added
H200 with steel shield
70000
60000
50000
40000
30000
20000
10000
0
0
100
200
300
400
500
X-Ray Calibration (continued)
With the steel shield in place, measurements (again
with the NIST-traceable ion chamber) were taken at
each of the 8 energies. The HVL filter wheel was
added, and the measurements repeatedmeasurements were within 2% of half-value.
Exposure and Dose Equivalent values were then
taken at both the 16 and 72 ft distances to give
approximately 15 mR/hr and 1 mR/hr exposure
distances for GM and scintillation detectors.
RESULTS:
A version of the 9DP (the Ludlum pressurized
ion chamber) has been developed to be
energy flat to H*(10) within 20 % from 40
keV to 1.3 MeV, and this result has been
verified by an independent lab.
More results to follow….