Precise measurements of the branching ratios for the flavor-changing neutral current decays K→πνν¯ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is ...important to measure both decay modes, K+→π+νν¯ and KL→π0νν¯, since different new physics models affect the rates for each channel differently. The NA62 experiment at the CERN SPS will measure the BR for the charged channel to better than 20%. The BR for the neutral channel has never been measured. We are designing the KLEVER experiment to measure BR( KL→π0νν¯) to ∼20% using a high-energy neutral beam at the CERN SPS. The boost from the high-energy beam facilitates the rejection of background channels such as KL → π0π0 by detection of the additional photons in the final state. On the other hand, the layout poses particular challenges for the design of the small-angle vetoes, which must reject photons from KL decays escaping through the beam exit amid an intense background from soft photons and neutrons in the beam. We present findings from our design studies, with an emphasis on the challenges faced and the potential sensitivity for the measurement of BR(KL→π0νν¯).
Precise measurements of the branching ratios for the K → π ν ν ¯ decays can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is important to measure both ...decay modes, K + → π + ν ν ¯ and K L 0 → π 0 ν ν ¯ , since different new physics models affect the rates for each channel differently. We are investigating the feasibility of performing a measurement of BR ( K L 0 → π 0 ν ν ¯ ) using a high-energy secondary neutral beam at the CERN SPS in a successor experiment to NA62. The planned experiment would reuse some of the NA62 infrastructure, including possibly the NA48 liquid-krypton calorimeter. The mean momentum of K L 0 mesons decaying in the fiducial volume is 70 GeV; the decay products are boosted forward, so that less demanding performance is required from the large-angle photon veto detectors. On the other hand, the layout poses particular challenges for the design of the small-angle vetoes, which must reject photons from K L 0 decays escaping through the beam pipe amidst an intense background from soft photons and neutrons in the beam. We present some preliminary conclusions from our feasibility studies, summarizing the design challenges faced and the sensitivity obtainable for the measurement of BR ( K L 0 → π 0 ν ν ¯ ) .
We present a global analysis of leptonic and semileptonic kaon decay data, including all recent results published by the BNL-E865, KLOE, KTeV, ISTRA+ and NA48 experiments. This analysis, in ...conjunction with precise lattice calculations of the hadronic matrix elements now available, leads to a very precise determination of |
V
us
| and allows us to perform several stringent tests of the Standard Model.
The Physics Beyond Colliders initiative is an exploratory study aimed at exploiting the full scientific potential of the CERN's accelerator complex and scientific infrastructures through projects ...complementary to the LHC and other possible future colliders. These projects will target fundamental physics questions in modern particle physics. This document presents the status of the proposals presented in the framework of the Beyond Standard Model physics working group, and explore their physics reach and the impact that CERN could have in the next 10-20 years on the international landscape.
Accurate measurements of physical processes in high energy frontier experiments demand exceptional spatial, temporal, and energy precision to discern the physics behind high-energy particle jets. ...Calorimeters, like other detection systems, must be able to meet these increasingly challenging performance requirements. In the prospective TeV-scale Muon Collider, the primary hurdle in designing detectors and devising event reconstruction algorithms is the challenge posed by Beam-Induced Background (BIB). Nevertheless, it is conceivable to mitigate the impact of BIB on the Muon Collider's calorimeter by capitalizing on certain characteristics and ensuring key features such as high granularity, precise timing, longitudinal segmentation, and superior energy resolution. This is what the here described Research and Development is trying to achieve with an innovative semi-homogeneous electromagnetic calorimeter constructed from stackable and interchangeable modules composed of lead fluoride crystals (PbF2). These modules are equipped with surface-mount UV-extended Silicon Photomultipliers (SiPMs) and are collectively referred to as the Crilin calorimeter (CRystal calorImeter with Longitudinal INformation). The challenge lies in making sure this calorimeter can operate effectively within an extremely harsh radiation environment, enduring an annual neutron flux of <inline-formula> <tex-math notation="LaTeX">10^{14}~n_{1\text {MeV}}/\text {cm}^{2} </tex-math></inline-formula> and a total ionizing dose (TID) of 10 kGy. In this article, the radiation tolerance measured in several irradiation campaigns is discussed, and the timing performances during a test beam at CERN-H2 with 120-GeV electrons. Additionally, a description of the latest prototype, Proto-1, is provided together with the results of the latest low-energy beam test at the LNF beam test facility (BTF) with 450 MeV electrons.
We have observed a significant enhancement in the energy deposition by 25–
100
GeV
photons in a
1
cm
thick tungsten crystal oriented along its
⟨
111
⟩
lattice axes. At
100
GeV
, this enhancement, ...with respect to the value observed without axial alignment, is more than twofold. This effect, together with the measured huge increase in secondary particle generation is ascribed to the acceleration of the electromagnetic shower development by the strong axial electric field. The experimental results have been critically compared with a newly developed Monte Carlo adapted for use with crystals of multi-
X
0
thickness. The results presented in this paper may prove to be of significant interest for the development of high-performance photon absorbers and highly compact electromagnetic calorimeters and beam dumps for use at the energy and intensity frontiers.
The measurement of BR(K+→π+νν̄) with 10% precision by the NA62 experiment requires extreme background suppression. The Small Angle Calorimeter aims to provide an efficient veto for photons flying at ...angles down to zero with respect to the kaon flight direction. The initial prototype was upgraded and tested at the Beam Test Facility of the DAΦNE Linac at Frascati. The energy resolution and the efficiency were measured and are presented.
In the first reported study of theory of mind (ToM; the ability to attribute mental states) in old age, Happeá, Winner, and Brownell (1998) observed better performance on ToM tasks in older ...participants (mean age 73 years) than in young participants (mean age 21 years). We present two experiments exploring the generality of this finding. Experiment 1 compared young, young‐old, and old‐old age groups (mean ages 19, 67, and 81 years, respectively) on their understanding of ToM stories both with and without the need to remember the information, and control studies that did not require the ability to attribute mental states. For ToM stories with a memory load, the young group performed significantly better than both the young‐old and old‐old groups; without a memory load, the young and young‐old groups performed significantly better than the old‐old group. In Experiment 2, young and old‐old age groups (mean ages 21 and 81 years, respectively) were compared on their understanding of ToM and control stories without the need to remember the information. Again, the young group performed significantly better than the old‐old group on ToM stories. There were no significant age differences in performance on the control stories in either experiment. The age deficit on ToM stories remained significant after taking account of measures of vocabulary and processing speed (Experiments 1 and 2), and measures of executive functioning (Experiment 2).
Crilin (Crystal Calorimeter with Longitudinal Information) is a semi-homogeneous, longitudinally segmented electromagnetic calorimeter based on high-
Z
, ultra-fast crystals with UV-extended SiPM ...readout. The Crilin design has been proposed as a candidate solution for both a future Muon Collider barrel ECAL and for the Small Angle Calorimeter of the HIKE experiment. As a part of the Crilin development program, we have carried out beam tests of small (10 × 10 × 40 mm
3
) lead fluoride (PbF
2
) and ultra-fast lead tungstate (PbWO
4
, PWO-UF) crystals with 120 GeV electrons at the CERN SPS to study the light yield, timing response, and systematics of light collection with a proposed readout scheme. For a single crystal of PbF
2
, corresponding to a single Crilin cell, a time resolution of better than 25 ps is obtained for
>
3 GeV of deposited energy. For a single cell of PWO-UF, a time resolution of better than 45 ps is obtained for the same range of deposited energy. This timing performance fully satisfies the design requirements for the Muon Collider and HIKE experiments. Further optimizations of the readout scheme and crystal surface preparation are expected to bring further improvements.
The K12 beamline for the KLEVER experiment van Dijk, M W U; Banerjee, D; Bernhard, J ...
Journal of physics. Conference series,
11/2019, Letnik:
1350, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The KLEVER experiment is proposed to run in the CERN ECN3 underground cavern from 2026 onward. The goal of the experiment is to measure BR(KL→π0vv¯), which could yield information about potential new ...physics, by itself and in combination with the measurement of BR(K+→π+vv¯) of NA62. A full description will be given of the considerations in designing the new K12 beamline for KLEVER, as obtained from a purpose made simulation with FLUKA. The high intensities required by KLEVER, 2 × 1013 protons on target every 16.8 s, with 5 × 1019 protons accumulated over 5 years, place stringent demands on adequate muon sweeping to minimize backgrounds in the detector. The target and primary dump need to be able to survive these demanding conditions, while respecting strict radiation protection criteria. A series of design choices will be shown to lead to a neutral beamline sufficiently capable of suppressing relevant backgrounds, such as photons generated by π0 decays in the target, and Λ → nπ0 decays, which mimic the signal decay.
PDF
