A large volume (4.8 m
3) liquid scintillator detector has been running in Hall C of the Gran Sasso Underground Laboratory since February 1995. This detector is called the “Counting Test Facility” ...(CTF). The main goal of the detector facility is the measurement of ultralow background levels in scintillators and the development of processes able to purify them at this level. The detector has been designed to have exceptional sensitivity using a variety of methods to identify backgrounds. With the CTF, records were achieved in the domain of low background large volume detectors. Limits of 3.5 ± 1.3 × 10
−16 g/g and 4.4
−1.2
+1.5 × 10
−16 g/g for the
238U and
232Th daughters, respectively, and 1.85 ± 0.13 ± 0.01 × 10
−18 for the isotopic abundance of
14C relative to
12C were obtained. These results are very encouraging and point towards the feasibility of low energy, real time scintillation detectors for solar neutrinos, such as Borexino.
We report the direct measurement of the 7Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV 7Be ...neutrinos is 49+/-3stat+/-4syst counts/(day.100 ton). The hypothesis of no oscillation for 7Be solar neutrinos is inconsistent with our measurement at the 4sigma C.L. Our result is the first direct measurement of the survival probability for solar nu(e) in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of 7Be, pp, and CNO solar nu(e), and the limit on the effective neutrino magnetic moment using solar neutrinos.
The target silicon detector for the FOCUS spectrometer Link, J.M; Reyes, M; Anjos, J.C ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2004, Volume:
516, Issue:
2
Journal Article
Peer reviewed
Open access
We describe a silicon microstrip detector interleaved with segments of a beryllium oxide target which was used in the FOCUS photoproduction experiment at Fermilab. The detector was designed to ...improve the vertex resolution and to enhance the reconstruction efficiency of short-lived charm particles.
Dalitz analysis is a powerful tool for physics studies within and beyond the Standard Model. In the last decade it has helped to investigate the Heavy Flavor hadronic decay dynamics and is now being ...applied to extract angles of the CKM Unitarity triangle. To perform such sophisticate analyses we need to model the strong interaction effects. The FOCUS experiment has performed pilot studies in the charm sector through the K-matrix formalism. What has been learnt from charm will be beneficial for future accurate beauty measurements. Experience and results from FOCUS are presented and discussed.
Using a high statistics sample of photo-produced charm particles from the FOCUS experiment at Fermilab, we report results of a search for eight rare and Standard-Model-forbidden decays: D+, ...Ds+→h±μ∓μ+ (with h=π,K). Improvement over previous results by a factor of 1.7–14 is realized. Our branching ratio upper limit D+→π+μ−μ+ of 8.8×10−6 at the 90% C.L. is below the current MSSM R-parity violating constraint.
The prototype of the Borexino detector Counting Test Facility, located in the Gran-Sasso laboratory, has been used to obtain a bound on the stability of the electron. The new lower limit on the mean ...lifetime defined on 32.1 days of data set is τ(e−→νe+γ)⩾4.6×1026 yr (90% c.l.).
We study the decay of Ds+ mesons into final states involving a KS0 and report the discovery of Cabibbo suppressed decay modes Ds+→KS0π−π+π+ (179±36 events) and Ds+→KS0π+ (113±26 events). The ...branching fraction ratios for the new modes are Γ(Ds+→KS0π−π+π+)Γ(Ds+→KS0K−π+π+)=0.18±0.04±0.05 and Γ(Ds+→KS0π+)Γ(Ds+→KS0K+)=0.104±0.024±0.014.
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