Radiation Damage in Quartz Fibers Exposed to Energetic Neutrons

1
Radiation Damage in Quartz Fibers Exposed to
Energetic Neutrons

• Peter Bruecken, Dylan Murray, Edwin Norbeck,
  Yasar Onel, John Stroh and Zak Rajput

2
The Experiment

• Seven types of quartz fibers were cleaved

• The fibers were loaded into an Ocean Optics
  SD2000 digital spectrometer

3
The Experiment

• Using a Xenon strobe for a source, the spectra of
  the fibers was measured before exposure (see
  chart)
• 2048 wavelength increments with 12-bit linear
  amplitude

4
The Experiment

• The fibers were exposed to radiation at the
  Intense Pulsed Neutron Source (IPNS) at Argonne
  National Laboratory

5
The Experiment

• The spectra of the fibers was then taken and
  compared to the spectra before the exposure

6
The Fibers

• Seven types of quartz-core quartz-clad fibers
  were used.
• 300 and 600 um core fibers were used
• Various types of quartz enhancements from the
  manufacturer were used.
• Fibers were fitted with removable connectors for
  radiation exposure

7
The dose

• IPNS produces neutrons by Uranium fission induced
  by a proton beam
• The fission reaction also produces gamma
  radiation
• 15 uA of 450 MeV protons over 313 hours (2 weeks)
  produced 7.42 x 1017 n/cm2
• Average fiber dose was calculated as 17.6 Mrad
  neutron and 91.1 Mrad gamma

8
The Results

• Most fiber-types showed attenuations of less than
  5 in the near UV to green wavelength range.
• A few fiber-types showed less attenuation in the
  near UV range.
• See the following graph for details

9
Results Attenuation Graph
10
Individual Fiber results

• Each spectra was plotted before and after the
  exposure on the following plots.
• The fiber numbers designate (all in mm)

TYPE
CORE CLAD DIAMETER
FVP 300 315 345
CORECLADBUFFER DIAMETER
CORE DIAMETER
11
Pre and Post Spectra FVP 300 315 345
12
Pre and Post Spectra FSHA 300 330 350
13
Pre and Post Spectra FDF 300 315 345
14
Pre and Post Spectra FBP 600 660 710
15
Pre and Post Spectra FVP 600 660 710
16
Pre and Post Spectra FVP 600 660 710 UVM
17
Pre and Post SpectraFSHA 600 630 800
18
Speculation

• All fibers had to sit dormant for 10 weeks
  following exposure before radiation levels
  allowed transport. During this time, some
  recovery of damage could have occurred.