In a special run of the LHC with Formula omitted km, proton-proton elastic-scattering events were recorded at Formula omitted TeV with an integrated luminosity of Formula omitted using the ALFA ...subdetector of ATLAS in 2016. The elastic cross section was measured differentially in the Mandelstam t variable in the range from Formula omitted GeV Formula omitted to Formula omitted GeV Formula omitted using 6.9 million elastic-scattering candidates. This paper presents measurements of the total cross section Formula omitted, parameters of the nuclear slope, and the Formula omitted-parameter defined as the ratio of the real part to the imaginary part of the elastic-scattering amplitude in the limit Formula omitted. These parameters are determined from a fit to the differential elastic cross section using the optical theorem and different parameterizations of the t-dependence. The results for Formula omitted and Formula omitted are sigmatot(ppright arrowX)=104.7±1.1mb,rho=0.098±0.011.The uncertainty in Formula omitted is dominated by the luminosity measurement, and in Formula omitted by imperfect knowledge of the detector alignment and by modelling of the nuclear amplitude.
The continuous emanation of Formula omitted from detector surfaces causes the dominant background in current liquid xenon time projection chambers (TPCs) searching for dark matter. A significant ...reduction is required for the next generation of detectors which are aiming to reach the neutrino floor, such as DARWIN. Formula omitted-induced backgrounds can be reduced using a hermetic TPC, in which the sensitive target volume is mechanically separated from the rest of the detector containing the majority of Rn-emanating surfaces. We present a hermetic TPC that mainly follows the well-established design of leading xenon TPCs and has been operated successfully over a period of several weeks. By scaling up the results achieved to the DARWIN-scale, we show that the hermetic TPC concept can reduce the Formula omitted concentration to the required level, even with imperfect separation of the volumes.
Abstract
A search for double-beta decay of
$$^{190}$$
190
Pt and
$$^{198}$$
198
Pt with emission of
$$\gamma $$
γ
-ray quanta was realized at the HADES underground laboratory with a 148 g platinum ...sample measured by two ultralow-background HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of
$$^{190}$$
190
Pt relative to different channels and modes of the decays were set on the level of
$$\lim T_{1/2}\sim 10^{14}$$
lim
T
1
/
2
∼
10
14
–
$$10^{16}$$
10
16
year. A possible exact resonant
$$0\nu KN$$
0
ν
K
N
transition to the 1,2 1326.9 keV level of
$$^{190}$$
190
Os is limited for the first time as
$$T_{1/2} \ge 2.5 \times 10^{16}$$
T
1
/
2
≥
2.5
×
10
16
year. A new lower limit on the double-beta decay of
$$^{198}$$
198
Pt to the first excited level of
$$^{198}$$
198
Hg was set as
$$T_{1/2} \ge 3.2\times 10^{19}$$
T
1
/
2
≥
3.2
×
10
19
year, one order of magnitude higher than the limit obtained in the previous experiment.
P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We ...have characterized a PPC detector's response to Formula omitted particles incident on the sensitive passivated and p Formula omitted surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the MajoranaDemonstrator experiment, a search for neutrinoless double-beta decay ( Formula omitted) in Formula omittedGe. Formula omitted decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of Formula omitted identification, reliably identifying Formula omitted background events on the passivated surface of the detector. We demonstrate effective rejection of all surface Formula omitted events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the Formula omitted region of interest window by an order of magnitude in the MajoranaDemonstrator and will be used in the upcoming LEGEND-200 experiment.
The process Formula omitted is studied in the center-of-mass energy range 1.17-2.00 GeV using data with an integrated luminosity of 201 pb Formula omitted collected by the SND detector at the ...VEPP-2000 Formula omitted collider. The Formula omitted cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the Formula omitted intermediate state. Our result on the Formula omitted cross section is consistent with the Formula omitted measurement in the Formula omitted mode. The search for radiative processes contributing to the Formula omitted cross section is performed, and no significant signal is observed.
This manuscript describes measurements of water-based liquid scintillators (WbLS), demonstrating separation of the Cherenkov and scintillation components using a low energy Formula omitted source and ...the fast timing response of a Large Area Picosecond Photodetector (LAPPD). Additionally, the time profiles of three WbLS mixtures, defined by the relative fractions of scintillating compound, are characterized, with improved sensitivity to the scintillator rise-time. The measurements were made using both an LAPPD and a conventional photomultiplier tube (PMT). All samples were measured with an effective resolution Formula omitted, which allows for the separation of Cherenkov and scintillation light (henceforth C/S separation) by selecting on the arrival time of the photons alone. The Cherenkov purity of the selected photons is greater than 60% in all cases, with greater than 80% achieved for a sample containing 1% scintillator. This is the first demonstration of the power of synthesizing low light yield scintillators, of which WbLS is the canonical example, with fast photodetectors, of which LAPPDs are an emerging leader, and has direct implication for future mid- and large-scale detectors, such as Theia, ANNIE, and AIT-NEO.
A technique is presented to measure the efficiency with which c-jets are mistagged as b-jets (mistagging efficiency) using Formula omitted events, where one of the W bosons decays into an electron or ...muon and a neutrino and the other decays into a quark-antiquark pair. The measurement utilises the relatively large and known Formula omitted branching ratio, which allows a measurement to be made in an inclusive c-jet sample. The data sample used was collected by the ATLAS detector at Formula omitted Formula omitted and corresponds to an integrated luminosity of 139 fb Formula omitted. Events are reconstructed using a kinematic likelihood technique which selects the mapping between jets and Formula omitted decay products that yields the highest likelihood value. The distribution of the b-tagging discriminant for jets from the hadronic W decays in data is compared with that in simulation to extract the mistagging efficiency as a function of jet transverse momentum. The total uncertainties are in the range 3-17%. The measurements generally agree with those in simulation but there are some differences in the region corresponding to the most stringent b-jet tagging requirement.
A search for chargino-neutralino pair production in three-lepton final states with missing transverse momentum is presented. The study is based on a dataset of Formula omitted TeV pp collisions ...recorded with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 Formula omitted. No significant excess relative to the Standard Model predictions is found in data. The results are interpreted in simplified models of supersymmetry, and statistically combined with results from a previous ATLAS search for compressed spectra in two-lepton final states. Various scenarios for the production and decay of charginos ( Formula omitted) and neutralinos ( Formula omitted) are considered. For pure higgsino Formula omitted pair-production scenarios, exclusion limits at 95% confidence level are set on Formula omitted masses up to 210 GeV. Limits are also set for pure wino Formula omitted pair production, on Formula omitted masses up to 640 GeV for decays via on-shell W and Z bosons, up to 300 GeV for decays via off-shell W and Z bosons, and up to 190 GeV for decays via W and Standard Model Higgs bosons.
The recent measurement of the muon anomalous magnetic moment by the Fermilab E989 experiment, when combined with the previous result at BNL, has confirmed the tension with the SM prediction at ...Formula omitted CL, strengthening the motivation for new physics in the leptonic sector. Among the different particle physics models that could account for such an excess, a gauged Formula omitted stands out for its simplicity. In this article, we explore how the combination of data from different future probes can help identify the nature of the new physics behind the muon anomalous magnetic moment. In particular, we contrast Formula omitted with an effective Formula omitted-type model. We first show that muon fixed target experiments (such as NA64 Formula omitted) will be able to measure the coupling of the hidden photon to the muon sector in the region compatible with Formula omitted, and will have some sensitivity to the hidden photon's mass. We then study how experiments looking for coherent elastic neutrino-nucleus scattering (CE Formula omittedNS) at spallation sources will provide crucial additional information on the kinetic mixing of the hidden photon. When combined with NA64 Formula omitted results, the exclusion limits (or reconstructed regions) of future CE Formula omittedNS detectors will also allow for a better measurement of the mediator mass. Finally, the observation of nuclear recoils from solar neutrinos in dark matter direct detection experiments will provide unique information about the coupling of the hidden photon to the tau sector. The signal expected for Formula omitted is larger than for Formula omitted with the same kinetic mixing, and future multi-ton liquid xenon proposals (such as DARWIN) have the potential to confirm the former over the latter. We determine the necessary exposure and energy threshold for a potential Formula omitted discovery of a Formula omitted boson, and we conclude that the future DARWIN observatory will be able to carry out this measurement if the experimental threshold is lowered to Formula omitted.
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