The beam and detector of the NA62 experiment at CERN

NA62 is a fixed-target experiment at the CERN SPS dedicated to measurements of rare kaon decays. Such measurements, like the branching fraction of the K+ → π+ ν bar nu decay, have the potential to bring significant insights into new physics processes when comparison is made with precise theoretical predictions. For this purpose, innovative techniques have been developed, in particular, in the domain of low-mass tracking devices. Detector construction spanned several years from 2009 to 2014. The collaboration started detector commissioning in 2014 and will collect data until the end of 2018. The beam line and detector components are described together with their early performance obtained from 2014 and 2015 data

Chapter 1: Introduction, scope, and schedule

The East Area of the CERN Proton Synchrotron has served the physics community for over 50 years and remains extremely popular and necessary, among other things, to complete full calibration over a large energy spectrum of the detectors to be installed in the Large Hadron Collider (LHC) experiments according to the needs of the upgrade for the High Luminosity LHC. In addition, physics programs like CLOUD, and test facilities such as IRRAD and CHARM are based on a reliable and easily maintainable East Area. This report summarizes the various detailed studies completed from 2016 to 2019

Instrument intercomparison in the pulsed neutron fields at the CERN HiRadMat facility

An intercomparison of the performances of active neutron detectors was carried out in pulsed neutron fi elds in the new HiRadMat facility at CERN. Five detectors were employed: four of them (two ionization chambers and two rem counters) are routinely employed in the CERN radiation monitoring system, while the fi fth is a novel instrument, called LUPIN, speci fi cally conceived for applications in pulsed neutron fi elds. The measurements were performed in the stray fi eld generated by a proton beam of very short duration with momentum of 440 GeV/c impinging on a dump. The beam intensity was steadily increased during the experiment by more than three orders of magnitude, with an H*(10) due to neutrons at the detector reference positions varying between a few nSv per burst and a few m Sv per burst, whereas the gamma contribution to the total H*(10) was negligible. The aim of the experiment was to evaluate the linearity of the detector response in extreme pulsed conditions as a function of the neutron burst in- tensity. The results show that the ionization chambers have a quasi-linear response, very close to the ideal behaviour also for values of H*(10) of a few m Sv/burst; the LUPIN response shows a slight deviation from the ideal curve when the H*(10) per burst is higher than 100 nSv; the rem counters response are characterized by a strong deviation from the linearity for H*(10) values higher than a few tens of nSv

Chapter 2: East Area renovationMotivations and general description

This chapter gives a general description of the East Area before and after Long Shutdown 2 (LS2)

Chapter 3: Design of the East Area facility after renovation

The PS primary proton beam is slowly extracted at 24 GeV/c towards the East Area with the help of the third- order resonance technique over a typical spill length of 350 to 450 ns within 2.4 s cycles. The number of East Area extractions is usually around five to six per overall PS super-cycle of typically 40 s and depends on both users and schedule constraints, respectively. After passing both magnetic septa SMH57 and SMH61 in the PS, the beam enters the F61 transfer line that transports the beam either to the so-called North Targets via the lines F62 and F63 or towards T08, which serves the irradiation facilities IRRAD and CHARM. During operation of primary ion beams, only these irradiation facilities can be operated. The principle of extraction by third-order resonance and the corresponding optical elements inside the PS, such as the magnetic septa, will be kept unchanged for the new East Area operation. Thus, only a replacement of the existing magnets by laminated versions with slight optimization of the optics was chosen as the renovation baseline for F61 with changes in the layout mostly due to integration constraints and considerations for improved radiation protection. In particular, all the main horizontal bends have been replaced by reliable and robust MCB magnets, which are available with sufficient spares and can be operated in pulsed mode. The splitting option, although more efficient for operation, was dropped in 2005 for technical reasons that were hard to overcome in a reliable manner. For further details on the recent operational history of F61 and the original ideas of the renovated East Area beams

Instrument intercomparison in the pulsed neutron fieldsat the CERN HiRadMat facility

An intercomparison of the performances of active neutron detectors was carried out in pulsed neutron fields in the new HiRadMat facility at CERN. Five detectors were employed: four of them (two ionization chambers and two rem counters) are routinely employed in the CERN radiation monitoring system, while the fifth is a novel instrument, called LUPIN, specifically conceived for applications in pulsed neutron fields. The measurements were performed in the stray field generated by a proton beam of very short duration with momentum of 440 GeV/c impinging on a dump. The beam intensity was steadily increased during the experiment by more than three orders of magnitude, with an H*(10) due to neutrons at the detector reference positions varying between a few nSv per burst and a few μSv per burst, whereas the gamma contribution to the total H*(10) was negligible. The aim of the experiment was to evaluate the linearity of the detector response in extreme pulsed conditions as a function of the neutron burst intensity. The results show that the ionization chambers have a quasi-linear response, very close to the ideal behaviour also for values of H*(10) of a few μSv/burst; the LUPIN response shows a slight deviation from the ideal curve when the H*(10) per burst is higher than 100 nSv; the rem counters response are characterized by a strong deviation from the linearity for H*(10) values higher than a few tens of nSv. © 2013 Elsevier Ltd. All rights reserved

Instrument intercomparison in the pulsed neutron fieldsat the CERN HiRadMat facility

An intercomparison of the performances of active neutron detectors was carried out in pulsed neutron fields in the new HiRadMat facility at CERN. Five detectors were employed: four of them (two ionization chambers and two rem counters) are routinely employed in the CERN radiation monitoring system, while the fifth is a novel instrument, called LUPIN, specifically conceived for applications in pulsed neutron fields

The CERN East Area Renovation

The East Area at CERN’s Proton Synchrotron delivers since over 56 years primary proton and ion beams as well as mixed secondary beams of hadrons, electrons and muons in a range of 0.5 GeV/c to 12 GeV/c. The CERN Management approved in 2016 a full renovation of this intensively used facility. It includes a new flexible beam design to meet todays physics requirements, which concern R&D; detector tests, samples analyses under high flux irradiation or physics studies (like the CLOUD experiment). This will result in the ability to run with highly pure electron, hadron or muon beams. The upgrade of the East Area also improves energy consumption with a pulsed powering scheme with new laminated magnets and energy recovering power converters that will reduce both power and cooling requirements. The renovation has already started. The first beam in the new East Area is expected to be delivered in 2021