Abstract
Abstract
Hadron fluence monitors based on static random access
memories (SRAMs) are in use at particle accelerators for the
protection of electronics and at proton-therapy facilities for
measuring secondary neutrons. One shortcoming of current solutions
is that they necessitate SRAMs to detect radiation-induced single
event upsets and require additional components to transfer the
counts from the radiation area. This approach limits the
practicality of the sensors due to their power requirements,
increased board complexity, larger physical footprint and reduced
total ionizing dose tolerance. In this work, we present proton
irradiation test results of a novel proton and neutron fluence
sensor we designed. The sensor is fully embedded in a SRAM-based
field programmable gate array (FPGA) solving the abovementioned
limitations of the state of the art. The FPGA configuration SRAM is
used as a sensitive element, while the Joint Test Action Group
interface is leveraged as a read out circuitry. We irradiated six
sensor units by means of a variable-energy proton beam at the Trento
Institute for Fundamental Physics and Applications (TIFPA, Trento,
Italy). We discuss our results in terms of proton to upset cross
section as a function of the proton energy in the range from 70 to
228 MeV, also parameterized with respect to the power supply
voltage. We evaluate the variability of the cross section in the set
of irradiated samples. Moreover, we show how we used the device to
image the proton beam and measure beam profiles for aligning the
configuration RAM and beam centers. We also suggest alternate
reading modes to measure the fluence on the device by measuring the
drawn current, rather than counting upsets.