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Self-Triggering Readout System for the Neutron Lifetime Experiment PENeLOPE
Abstract
The aim of PENeLOPE (Precision Experiment on Neutron Lifetime Operating with Proton Extraction) at the Forschungsreaktor Munchen II is a high-precision measurement of the neutron lifetime and thereby an improvement of the parameter's precision by one order of magnitude. In order to achieve a higher accuracy, modern experiments naturally require state-of-the-art readout electronics, as well as high-performance data acquisition systems. This paper presents the self-triggering readout system designed for PENeLOPE which features a continuous pedestal tracking, configurable signal detection logic, floating ground up to 30 kV, cryogenic environment and the novel Switched Enabling Protocol (SEP). The SEP is a time-division multiplexing transport level protocol developed for a star network topology.
... Our study highlights the importance of improving the precision of the alternative independent determinations of G CKM F and G EW F in order to confirm or refute BSM contributions to the Fermi constant. Concerning G CKM F , improvements in the determination of jV ud j should arise from advances in nuclear-structure [99,100] and EW radiative corrections [101], while experimental developments [102][103][104][105][106][107][108] could make the determination from neutron decay [109][110][111] competitive and, in combination with K l3 decays, add another complementary constraint on jV ud j=jV us j via pion β decay [112,113]. Furthermore, improved measurements of jV cd j from D decays [114] could bring the precision of the first-column CKM unitarity relation close to the first-row one, which, in turn, could be corroborated via improved jV us j determinations from K l3 decays [115][116][117]. ...
The Fermi constant GF is extremely well measured through the muon lifetime, defining one of the key fundamental parameters in the standard model (SM). Therefore, to search for physics beyond the SM (BSM) via GF, the constraining power is determined by the precision of the second-best independent determination of GF. The best alternative extractions of GF proceed either via the global electroweak (EW) fit or from superallowed β decays in combination with the Cabibbo angle measured in kaon, τ, or D decays. Both variants display some tension with GF from muon decay, albeit in opposite directions, reflecting the known tensions within the EW fit and hints for the apparent violation of Cabibbo-Kobayashi-Maskawa unitarity, respectively. We investigate how BSM physics could bring the three determinations of GF into agreement using SM effective field theory and comment on future perspectives.
... Our study highlights the importance of improving the precision of the alternative independent determinations of G CKM F and G EW F in order to confirm or refute BSM contributions to the Fermi constant. Concerning G CKM F , improvements in the determination of |V ud | should arise from advances in nuclear-structure [90,91] and EW radiative corrections [92], while experimental developments [93][94][95][96][97][98][99] could make the determination from neutron decay [100][101][102] competitive and, in combination with K 3 decays, add another complementary constraint on |V ud |/|V us | via pion β decay [103,104]. Further, improved measurements of |V cd | from D decays [105] could bring the precision of the first-column CKM unitarity relation close to the first-row one, which, in turn, could be corroborated via improved |V us | determinations from K 3 decays [106][107][108]. ...
The Fermi constant () is extremely well measured through the muon lifetime, defining one of the key fundamental parameters in the Standard Model (SM). However, to search for physics beyond the SM (BSM), it is the precision of the second-best independent determination of that defines the sensitivity. The best alternative extractions of proceed via the global electroweak (EW) fit or from superallowed decays in combination with the Cabibbo angle measured in kaon, , or D decays. Both variants display some tension with from muon decay, albeit in opposite directions, reflecting the known tensions within the EW fit and hints for the apparent violation of CKM unitarity, respectively. We investigate how BSM physics could bring the three determinations of into agreement using SM effective field theory and comment on future perspectives.
... In addition to the long-standing discrepancy between bottle and beam measurements (see Refs. [7,95] for reviews), also the difference between recent bottle measurements [8,96,97] currently leads to a non-negligible scale factor in the PDG average [3]. Fortunately, there are plans to probe τ n at a level down to hundreds of ms [98][99][100][101]. ...
Nuclear decays as well as the decay of the neutron are well-established low-energy probes of physics beyond the Standard Model (SM). In particular, with the axial-vector coupling of the nucleon determined from lattice QCD, the comparison between experiment and SM prediction is commonly used to derive constraints on right-handed currents. Further, in addition to the CKM element from kaon decays, from decays is a critical input for the test of CKM unitarity. Here, we point out that the available information on decays can be re-interpreted as a stringent test of lepton flavor universality (LFU). In fact, we find that the ratio of from kaon decays over from decays (assuming CKM unitarity) is extremely sensitive to LFU violation (LFUV) in W-- couplings thanks to a CKM enhancement by . From this perspective, recent hints for the violation of CKM unitarity can be viewed as further evidence for LFUV, fitting into the existing picture exhibited by semi-leptonic B decays and the anomalous magnetic moments of muon and electron. Finally, we comment on the future sensitivity that can be reached with this LFU violating observable and discuss complementary probes of LFU that may reach a similar level of precision, such as at the PEN experiment or even direct measurements of at an FCC-ee.
Nuclear β decays as well as the decay of the neutron are well-established low-energy probes of physics beyond the standard model (SM). In particular, with the axial-vector coupling of the nucleon g_{A} determined from lattice QCD, the comparison between experiment and SM prediction is commonly used to derive constraints on right-handed currents. Further, in addition to the CKM element V_{us} from kaon decays, V_{ud} from β decays is a critical input for the test of CKM unitarity. Here, we point out that the available information on β decays can be reinterpreted as a stringent test of lepton flavor universality (LFU). In fact, we find that the ratio of V_{us} from kaon decays over V_{us} from β decays (assuming CKM unitarity) is extremely sensitive to LFU violation (LFUV) in W-μ-ν couplings thanks to a CKM enhancement by (V_{ud}/V_{us})^{2}∼20. From this perspective, recent hints for the violation of CKM unitarity can be viewed as further evidence for LFUV, fitting into the existing picture exhibited by semileptonic B decays and the anomalous magnetic moments of muon and electron. Finally, we comment on the future sensitivity that can be reached with this LFU violating observable and discuss complementary probes of LFU that may reach a similar level of precision, such as Γ(π→μν)/Γ(π→eν) at the PEN and PiENu experiments or even direct measurements of W→μν at an FCC-ee.
In this paper we present the FPGA-based framework IFDAQ which is used for the development of data acquisition systems for detectors in high energy physics. The framework supports Xilinx FPGA and provides a collection of IP cores written in VHDL which use the common interconnect interface. The IP core library offers functionality required for the development of the full DAQ chain. The library consists of SERDES-based TDC channels, an interface to a multi-channel 80 MS/s 10-bit ADC, data transmission and synchronization protocol between FPGAs, event builder and slow control. The functionality is distributed among FPGA modules built in the AMC form factor: front-end and data concentrator. This modular design also helps to scale and adapt the data acquisition system to the needs of the particular experiment. The first application of the IFDAQ framework is the upgrade of the read-out electronics for the drift chambers and the electromagnetic calorimeters of the COMPASS experiment at CERN. The framework will be presented and discussed in the context of this upgrade.
PENeLOPE is a neutron lifetime measurement developed at the Technische Universität München and located at the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) aiming to achieve a precision of 0.1 seconds. The detector for PENeLOPE consists of about 1250 Avalanche Photodiodes (APDs) with a total active area of 1225 cm2. The decay proton detector and electronics will be operated at a high electrostatic potential of −30 kV and a magnetic field of 0.6 T. This includes shaper, preamplifier, ADC and FPGA cards. In addition, the APDs will be cooled to 77 K. The 1250 APDs are divided into 14 groups of 96 channels, including spares. A 12-bit ADC digitizes the detector signals with 1 MSps. A firmware was developed for the detector including a self-triggering readout with continuous pedestal calculation and configurable signal detection. The data transmission and configuration is done via the Switched Enabling Protocol (SEP). It is a time-division multiplexing low layer protocol which provides determined latency for time critical messages, IPBus, and JTAG interfaces. The network has a n:1 topology, reducing the number of optical links.
The PANDA data acquisition system will operate in trigger-less mode and collect about 100 GBytes of data per second from more than a thousand front-end modules. The information from all detectors is combined into data blocks, every block corresponds to 500 microseconds of beam. The SODA (Synchronization Of Data Acquisition) project aims to develop a versatile optical network system which is, first of all, able to provide a common reference time with a precision better than 20 ps R.M.S. In addition, the system synchronizes data taking with the burst structure and performs monitoring of data acquisition modules. Furthermore, it takes responsibility for data flow control. The core of the system is a point-to-multipoint bidirectional optical link which is able to broadcast information from a master module to few hundred destinations and to acquire information from the destination modules via a passive optical fiber network. The first prototype system has been built and tested. The architecture of the SODA system, the hardware implementation and the performance parameters of the prototype system are discussed.