Target book
#Methods
0 and 180
The target is bombarded with a beam of alpha particles (works best; higher eloss) with the active layer either facing towards or away from the beam. Higher beam energies gives better separation.
The target thickness is inferred from the shift in energy.
Rutherford back scattering (RBS)
The target is bombarded with a beam. Alphas particles gives better separation and ensure the elastic cross section is Rutherford to higher energies.
The target thickness can then be inferred from the yield relative of two layers: \[ \frac{N_A}{N_B} = \frac{\rho_A t_A Z_A^2}{\rho_B t_B Z_B^2}, \] normalization can normally be done relative to the backing.
That the cross section is Rutherford can be verified from the angular and energy dependence.
Inelastic yield
Essentially normalizing to a known cross section.
#Boron
Summer 2016 target
- Runs: 1593-1897
- Manufacturing: The target was manufactured from >99% enriched B11 by evaporation in a Copper crucible. It contains traces of Cu.
- Thickness runs: 1854-1857. The latter two off the beam spot.
- Analysis method: 0 and 180 degrees.
- Thickness: 12.6 ± 1.2 ug/cm²
- Analysis method: RBS normalizing to backing.
- Thickness: 11.5 ± 1.4 ug/cm²
Analysis: https://elog.kern.phys.au.dk/Subatom/293
November 2016 batch
The target was manufactured from >99% enriched B11 by evaporation in a Carbon crucible.
Carbon from the crucible was evaporated during manufacturing. Hence target is a mixture of C and B.
November 2016 target
- Runs: 1923-2086
- Manufacturing: See above
- Thickness runs: 2085-2086.
- Analysis method: 0 and 180 degrees.
- Thickness: 16±4 µg/cm²
Carbon from the crucible was evaporated during manufacturing. Hence target is a mixture of C and B.
Target destroyed during a target change the ~ 9/2 2017
February 2017 target
- Runs: 2115-2185
- Manufacturing: See above
- Thickness runs: 2113-2114.
- Analysis method: RBS normalizing to backing.
- Thickness: ~12 ug/cm² (but probably quite uncertain)
Spectra in ring 13 of the SU. From low to high energy. Boron, target Carbon and backing Carbon.
Carbon backing is 4µg/cm² ± 10%.
Target destroyed during a target change the 5/4 2017
June 2017 batch
The target was manufactured from >99% enriched B11 by evaporation in a Cu crucible.
The crucible was heavily loaded and evaporation was performed slowly in order to minimize Cu contamination. Folmer is unsure if thickness. Guess is 10-20 ug. Backing is laser ablated Carbon. 4 ug/cm^2
In terms of background components these targets seems clean.
Thin batch
Numbered 21, 22, 24, 25, 26.
Thick batch
Numbered is 18, 27, 29, 6 and 5.
Target #18
- Runs: 2247-
- Manufacturing: See above
- Thickness runs: 2247-2248
- Analysis method: 0 and 180 degrees.
- Thickness: 3.44 ± 0.25 ug/cm2
29/6 2017 batch
Numbered is 7, 19, 23, 51
Target #23
- Mounted 23/8-2017
- Runs: 2393-
- Manufacturing: See above
- Thickness runs: 2393-2394
- Analysis method: Peak width
- Thickness: Folmer ~120nm. Analysis 140±10nm
#Lithium
February 2017 target
- Runs: 2107-2150
- Manufacturing: The target was manufactured from >99.9% enriched Li7. A layer of Carbon was added after the Lithium.
- Thickness runs: 2107-2112 (0 and 180). 2146 (yield test)
- Analysis method: Inelastic yield
- Thickness: 1 ± 1 ug/cm²
According to ENDF the inelastic cross section for 7Li(p,a)a is 1.47mb. Run 2146 contains 16µC (probably H+). We observed 1318 counts and the mul=2 detection efficiency is 17.7%.
Target was brownish and quite wrinkled. When removing it, a small hole was observed. Picture of target
Target destroyed during a target change the 10/3 2017
June 2017 target
Batch: 30, 31, 33, 37.
30
- Runs: 2259-2286
- Manufacturing: The target was manufactured from >99.9% enriched Li7. Thin layer of B10 was deposited before the 7Li to protect the C backing.
- Thickness runs: 22262 (yield test)
- Analysis method: Inelastic yield
- Thickness: 480 nm
Target is white and very transparent. Same procedure as above.
Additional counts observed at ~4MeV. We suspect B11.
Target destroyed during a target change the 15/6 2017
#LiF
Thin targets
- Batch: Unknown
- Runs: 2287-2311, 2362-2384
- Manufacturing: Natural LiF evaporated onto 4ug/cm^2 C backing.
- Thickness: 280Å (Folmer - Quartz chrystal), 7.83ug/cm² ± 10% (297nm) from inelastic yield
June 2017 target
- Batch: 28, 33, 36, 39.
- Manufacturing: Natural LiF evaporated onto 4ug/cm^2 C backing.
- Thickness: 900Å (Folmer - Quartz chrystal)
