Intro. LHC Layout Irrad. Damages

2011-2012 Irrad. Measured Levels 2015 (2016) Irrad. Measured Levels 2017-2023 Irrad. Expected Levels

HL-LHC Irrad.Expected Levels R2E Mitigation Program Irrad. Expected Spectra

Introduction

LHC environement is specific, being different from known radiation environements like space or nuclear plants, for 2 main reasons:

• Type of radation and particle type and energy ranges.
• Failure dependance, not as critical as in space applications (acceptable non-null failure rate).

LHC Layout

Irradiations conditions will be dependent on the machine location, regarding identified main sources (combinations possible in some locations):

• Collimator-like Losses (beam cleanning, injection protection and dump protection).
• Particles secondaries (debris from beam collisions at expermiments mainly lost in the accelerator part adjacent to the experiments).
• Beam-Gas interaction. (collisions of beam particles with residual gas; gas-density is non-zero in vacuum)

LHC Sensitive to radiation Areas after R2E Mitigation Program (re-location + shielding) .png

Irradiation Expected Damages

Electronic devices exposed to radiation can experience 3 different types of radiation damage:

• T.I.D.    : Total Ionising Dose (cumulative).
• N.I.E.L. : Non-Ionising Energy Loss (cumulative), 1 MeV equivalent neutron fluence. (Displacement Damage).
• S.E.E.    : Single Event Effect, proportionnal to High Energy Hardon fluence (with Energies above a few MeV typically 20 MeV), and also depending on the component sensitivity to the Thermal Neutrons (E < 0.5 eV).

A very basic file is provided below with number of equipements per location, giving an estimate of the number of events which can be expected based on the High Energy Hadrons Fluence and each converter sensitivity.

• SY-EPC LHC Events Irradiation Calculator .xls, and for consultation only .htm

R2E Mitigation Program

[2011; 2012] Irradiations Measured Levels

[2015] Irradiations Measured Levels

[2016] Irradiations Measured Levels

[2017; 2018] Irradiations Expected Levels

This period ends up with LS2, where new radiation-tolerant converters will be installed. In 2017-02, FGClite controllers were installed on all LHC60A-08V.
Status and evolution of radiation on 60A power converters, by Ruben Garcia - presented in TE-TM .indico
Update on the expected radiation levels for HL-LHC, by Ruben Garcia - presented in HL-LHC 8th collaboration week in 2018-10-17. .pdf

Radiation levels and converters location after LS1

[2020; 2023] Irradiations Expected Levels

R2E-LHC600A, R2E-HL-LHC600A, R2E-LHC4-6-8kA converters are installed, with FGClite being installed in remaining places (RR1/5/7).

Radiation levels and converters location after LS2

[2025; 2035] Irradiations Expected Levels

HL-LHC upgrade will impact a lot the radiation levels on all sensitive places, since the luminosity will increase from 30 fb^-1 to 250 fb^-1 per year, for a total of 4 000 fb^-1 for HL-LHC era (12 years).

A common factor can very often being used:
1 Gy <=> 1E9 E>20MeV hadrons [/(cm².year)] <=> 1E10 1MeV neutrons eq. [nb/(cm².year)] <=> 1E10 thermal neutrons [nb/(cm².year)]

HL-LHC radiation level specification document 2020-09
HL-LHC radiation level specification document and review @ 2019-12
Last Official R2E-validated Radiation levels @ 2019-09
Update on 60A radiation levels in LHC arc (2019-09 .pdf)
HL-LHC radiation levels in the IP1-IP5 LSS tunnel and RRs, from data here (2019-04 .pdf)
HL-LHC Integration Meeting: ... R2E mapping in DS areas of IR1 and IR5... (2018-11 .pdf)
HL-LHC TCC (2017-11 .pdf)
Informal meeting Yves + Ruben (2018-01-31) in Yves's Office + MCWG (2018-01 .pdf)
6th Annual HiLumi Collaboration Meeting, Paris, November 14-16 2016, from data here (2016-11 .pdf)
R2E Mitigation Levels (after HL-LHC Upgrade foreseen in 2023), from data here (2013-11 .pdf)

Irradiation Expected Spectra

See following curves detailling the radiation type vs LHC locations (UJ/RR locations dominated by neutrons since shielded, then stopping the protons more efficiently than neutrons) .

Particle energy spectra (lethargy) and Inverse cumulative high energy hadron fluence for UJ-14/16 & RR-13/17 in the LHC < 2011-12
(more shielded planned to be added in end of 2011).
Curves normalized to a nominal year of operation.

Particle energy spectra (lethargy) and Inverse cumulative probability plots representative for tunnel areas in the LHC.
Spectra normalized one proton-proton collision (referred to as a primary in the label). Peak seen at lower Ej for the proton fluence due to (n,p) reactions with Nitrogen in air.
Curves normalized to the high Ej hadron fluence.

References

An overview of the radiation environment at the LHC in light of R2E activities .pdf