Tuesday, 9 December 2014

Visiting iThemba Labs in Cape Town: Investigating capabilities of Single Even Upset studies with protons and neutrons

Milos Lokajicek, Ivo Polak, from the Institute of Physics of the Czech Academy of Sciences, and myself visited the beam-lines and halls of iThemba Labs in Cape Town. Siegfried Fortsch organised the visit. We met with nuclear physicists involved in single-event upset (SEU)studies for aerospace-related projects. We also met with the head of the accelerator division, Lowry Conradie. The aim of the visit is to learn about the capabilities and conditions for SEUs of electronics. In short:

Protons can be provided with energies up to 200 MeV and currents ranging between 0.5 nA and multiples of micro-A (which is far more than we need). Beams with 66 MeV can be provided on parasitic mode when ion implantation and medical physics do not use beams. Beams can be defocused to 1cm x 1cm with reasonable homogeneity.  The A-line is preferred for proton beams (see pictures below).

Monochromatic neutrons can be provided in the range between 40 and 200 MeV with fluxes that ranges between 4.7 10^4 cm^{-2} s^{-1} (at 66 MeV) and 4.6 10^{3} cm^{-2} s^{-1} (at 200 MeV). The beam size is about 10 cm x 10 cm. Dose measurements are provided by the lab. The D-line is preferred for neutron beams (see pictures below). It is important to note that the energy range provided is unique and the metrology community comes regularly to iThemba to perform measurements.

Below is a picture of the head of the accelerator division, Lowry Conradie. To the right, on the board is the schematic of the different facilities in the lab.

A close up of the facilities at iThemba - Cape. The "star" corresponds to the cyclotron.

Below is a picture of the run control

Siegfried Fortsch points to the current monitor. At the time of the picture over 200 micro-A of protons were being provided to the ion implantation folks.

Below is a picture of the A-line (preferred for proton studies). In blue is the vacuum chamber.

Quadrupole magnets in the A-line, upstream of the vacuum chamber

Below is a picture of the feedthroughs of the vacuum chamber on the A-line.

Opened the vacuum chamber in the A-line. Below is a future of the inside of the chamber. To the left is the orifice of the promo beam. At the centre is a possible location of the target. After discussion with experts placing the samples holders on one of the arms seems the preferred option.

A close-up of one of the arms where we will place the the sample holders. Siegie will pass the drawings for the workshop at Wits to design the holder.

Inside the hall of the D-line (neutron beam). Neutron flux measurements are provided by the lab.

Close-up of the table where the samples will be located on the D-line.

Below is a picture of the data acquisition system (analog) from the different halls and lines.

Many thanks to Siegie for setting this up!

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