P. Peronnard

A New RadMon Version for the LHC and its Injection Lines

A system to monitor the radiation levels is required in the Large Hadron Collider (LHC) and its injection lines in order to quantify the radiation effects on electronics. Thus, the RadMons were installed in critical areas where equipment is or will be placed. The first years of operation, successive test campaigns and new requirements, raised the need for a new design of the monitor. The architecture of the new RadMon, the radiation reliability and the design strategy adopted for the sensors, used for monitoring the mixed radiation field of the LHC accelerator, are described highlighting the achieved improvements in terms of radiation robustness and measurement accuracy of a device which is of interest for many other research institutes.

The LHC Radiation Monitoring System - RadMon

Julien Mekki, Sergio Batuca, Markus Brugger, Marco Calviani, Alfredo Ferrari, Daniel Kramer, Roberto Losito, Alessandro Masi, Anna Nyul, Paul Peronnard, Christian Pignard, Ketil Roeed, Thijs Wijnands CERN CERN CH-1211, Geneve 23, Switzerland E-mail:; Julien.Mekki@cern.ch; Sergio.batuca@cern.ch; Markus.Brugger@cern.ch; Marco.Calviani@cern.ch, Alfredo.Ferrari@cern.ch; Daniel.kramer@cern.ch; Roberto.Losito@cern.ch; Alessandro.Masi@cern.ch; Ana.Nyul@cern.ch; Paul.Peronnard@cern.ch; Christian.Pignard@cern.ch; Ketil.Roeed@cern.ch; Thijs.Wijnands@cern.ch

Method for measuring mixed field radiation levels relevant for SEEs at the LHC

At the LHC installed electronics will be exposed to a radiation field of mixed particles over a wide range of energies. While Monte Carlo transport codes can be used for calculations and predictions of radiation levels, the complex operation and layout of the LHC accelerator give rise to significant uncertainties. Dedicated radiation monitors are therefore installed in locations of the electronics to provide an on line measurement of the radiation levels. This paper addresses the method that has been applied to calibrate these radiation monitors for their use in mixed radiation fields. New irradiation tests to determine the sensitivity to neutrons from a few MeV to 20 MeV will be presented along with additional irradiation tests with high energy protons.

In Flight SEU/MCU Sensitivity of Commercial Nanometric SRAMs: Operational Estimations

A method and the corresponding platform devoted to operational SEE-rate prediction are presented and illustrated by experimental results. Predicted error-rates are in well agreement with results issued from the activation of an SRAM platform, in 90 nm technology node, on board stratospheric balloons flights. Direct ionization of protons is investigated for a 65 SRAM memory virtually boarded on the balloon flight.

Qualification and Characterization of SRAM Memories Used as Radiation Sensors in the LHC

An 8 Mbit 90-nm memory is proposed as a new high energy hadron fluence sensor. The obtained cross sections for protons (30 MeV up to 480 MeV) and thermal neutrons as well as their dependency on the TID together with the control circuitry is presented. Burst events were recorded during irradiation and an analysis on the causes has been performed proposing an algorithm to mitigate and correct the burst multiple events. Finally, the effects of the energy dependency on the measurements in the LHC mixed radiation field are discussed.

New Testing Methodology of an Analog to Digital Converter for the LHC Mixed Radiation Field

In this work a commercial off the shelf Analog to Digital Converter (ADC), based on a Successive Approximation Register (SAR) structure, has been tested to verify Total Ionizing Dose (TID) effects and evaluate Single Event Upset (SEU) and Single Event Latch-up (SEL) cross sections. A well-known test is used to verify the SEU cross section with a constant input voltage; a new test method is proposed to measure the dynamic ADC performance, such as the Effective Number Of Bit (ENOB), continuously during the irradiation. The tests have been carried out at the Paul Scherrer Institute (PSI) beam facility at 230 MeV, at CERN in a dedicated experimental area that recreates the same radiation environment of the Large Hadron Collider (LHC) tunnel, and at a heavy ion facility, especially for defining the SEL risk.

Analysis of SEL on Commercial SRAM Memories and Mixed-Field Characterization of a Latchup Detection Circuit for LEO Space Applications

A single event latchup (SEL) experiment based on commercial static random access memory (SRAM) memories has recently been proposed in the framework of the European Organization for Nuclear Research (CERN) Latchup Experiment and Student Satellite nanosatellite low Earth orbit (LEO) space mission. SEL characterization of three commercial SRAM memories has been carried out at the Paul Scherrer Institut (PSI) facility, using monoenergetic focused proton beams and different acquisition setups. The best target candidate was selected and a circuit for SEL detection has been proposed and tested at CERN, in the CERN High Energy AcceleRator Mixed-field facility (CHARM). Experimental results were carried out at test locations representative of the LEO environment, thus providing a full characterization of the SRAM cross sections, together with the analysis of the single-event effect and total ionizing dose of the latchup detection circuit in relation to the particle spectra expected during mission. The setups used for SEL monitoring are described, and details of the proposed circuit components and topology are presented. Experimental results obtained both at PSI and at CHARM facilities are discussed.

Analysis of SEL on commercial SRAM memories for latchup detection and protection in LEO space applications

SEL characterization of commercial SRAM memories has been carried out to select the best candidate for a latchup experiment in LEO space environment. A circuit for SEL detection and protection has been proposed and tested at CERN in the CHARM mixed-field facility.

Embedded Detection and Correction of SEU Bursts in SRAM Memories Used as Radiation Detectors

SRAM memories are widely used as particle fluence detectors in high radiation environments, such as in the Radiation Monitoring System (RadMon) currently in operation in the CERN accelerator complex. Multiple Cell Upsets (MCUs), arising from micro-latchup events, are characterized by a large number of SEUs, ultimately affecting the measurement of particle fluxes and resulting in corrupted data and accuracy losses. A study of the generation of this type of SEU bursts was performed on an 8 Mbit 90-nm SRAM memory. Experimental tests were carried out with a focused beam of protons on target as well as in a mixed field environment dominated by high energy hadrons. A solution approach using an on-line detection and correction algorithm embedded on an FPGA was investigated and evaluated for use on a RadMon device.

Analysis and Detection of Multiple Cell Upsets in SRAM Memories Used as Particle Detectors

SRAM memories are widely used as particle detectors in high radiation environments, as in the CERN accelerator complex. Multiple Cell Upsets (MCUs) characterized by a large number of SEUs may affect the measurement of particle fluxes, resulting in corrupted data and accuracy losses. A study of SEU bursts generation was carried out on an 8 Mbit 90-nm memory and a solution approach using a detection and correction algorithm implemented on an FPGA was investigated.