We present a new measurement of the positive muon magnetic anomaly, a µ ≡ (gµ − 2)/2, from the Fermilab Muon g −2 Experiment based on data collected in 2019 and 2020. We have analyzed more than four times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of two due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, ω′ p , and of the anomalous precession frequency corrected for beam dynamics effects, ωa. From the ratio ωa/ω ′ p , together with precisely determined external parameters, we determine a µ = 116 592 057(25) × 10 −11 (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a µ (FNAL) = 116 592 055(24) × 10 −11 (0.20 ppm). The new experimental world average is aµ(Exp) = 116 592 059(22) × 10 −11 (0.19 ppm), which represents a factor of two improvement in precision.

The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ.

We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below 10 GeV/c2. This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c2 and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.

We report results from a blind analysis of the final data taken with the Cryogenic Dark Matter Search experiment (CDMS II) at the Soudan Underground Laboratory, Minnesota, USA. A total raw exposure of 612 kg-days was analyzed for this work. We observed two events in the signal region; based on our background estimate, the probability of observing two or more background events is 23%. These data set an upper limit on the Weakly Interacting Massive Particle (WIMP)-nucleon elastic-scattering spin-independent cross-section of 7.0 × 10 −44 cm 2 for a WIMP of mass 70 GeV/c 2 at the 90% confidence level. Combining this result with all previous CDMS II data gives an upper limit on the WIMP-nucleon spin-independent cross-section of 3.8 × 10 −44 cm 2 for a WIMP of mass 70 GeV/c 2 . We also exclude new parameter space in recently proposed inelastic dark matter models. Cosmological observations [1] have led to a concordance model of the universe where ∼85% of matter is non-baryonic, non-luminous and non-relativistic at the time of structure formation. Weakly Interacting Massive Particles (WIMPs) [2] are a class of candidates for this dark matter which are particularly well motivated by proposed extensions to the Standard Model of particle physics and by thermal production models for dark matter in the early universe [3,4,5,6]. WIMPs, distributed in a halo surrounding our galaxy, would coherently scatter off nuclei in terrestrial detectors [7,8,9] with a mean recoil energy of ∼ tens of keV, presently limited by observation to a rate of less than 0.1 event 5,6,10]. Direct search experiments seek recoil signatures of these interactions and have achieved the sensitivity to begin testing the most interesting classes of WIMP models [11,12,13,14].The Cryogenic Dark Matter Search (CDMS II) experiment, located at the Soudan Underground Laboratory, uses 19 Ge (∼230 g) and 11 Si (∼100 g) particle detectors operated at cryogenic temperatures (< 50 mK) [11,15]. Each detector is a disk ∼10 mm thick and 76 mm in diameter. Particle interactions in the detectors deposit energy in the form of phonons and ionization. Phonon sensors on the top of each detector are connected to four phonon readout channels to allow measurement of the recoil enarXiv:0912.3592v1 [astro-ph.CO]

We observe a signal for the doubly charmed baryon Xi(+)(cc) in the charged decay mode Xi(+)(cc)-->Lambda(+)(c)K-pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence.