The CLEO III drift chamber Peterson, D; Berkelman, K; Briere, R ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2002, Letnik:
478, Številka:
1
Journal Article
Recenzirano
The CLEO group at the Cornell Electron Storage Ring has constructed and commissioned a new central drift chamber. With 9796 cells arranged in 47 layers ranging in radius from 13.2 to
79
cm
, the new ...drift chamber has a smaller outer radius and fewer wires than the drift chamber it replaces, but allows the CLEO tracking system to have improved momentum resolution. Reduced scattering material in the chamber gas and in the inner skin separating the drift chamber from the silicon vertex detector provides a reduction of the multiple scattering component of the momentum resolution and an extension of the usable measurement length into the silicon. Momentum resolution is further improved through quality control in wire positioning and symmetry of the electric fields in the drift cells which have provided a reduction in the spatial resolution to
88
μm
(averaged over the full drift range).
Flavor physics in the quark sector Asner, D.M.; Bauer, D.; Becher, T. ...
Physics Reports,
2010, Letnik:
494, Številka:
3
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical ...interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved; apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral
K
mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral
B
mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of
K
,
D
, and
B
mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model.
In the near future, there will be a transition from the current to a new generation of experiments; thus a review of the status of quark flavor physics is timely. This report is the result of the work of physicists attending the 5th CKM workshop, hosted by the University of Rome “La Sapienza”, September 9–13, 2008. It summarizes the results of the current generation of experiments that are about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade.
Luminosity monitoring and measurement at CDF Cronin-Hennessy, D.; Beretvas, A.; Derwent, P.F.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2000, Letnik:
443, Številka:
1
Journal Article
Recenzirano
Using two telescopes of beam–beam counters, CDF (Collider Detector at Fermilab) has measured the luminosity to an accuracy of 4.1% (3.6%) in run Ib (Ia). For run Ib (Ia) the average luminosity was
...9.1(3.3)×10
30
cm
−2
s
−1
. For a typical data set the integrated luminosity was
86.47
(19.65)
pb
−1
in run Ib (Ia) resulting in a total integrated luminosity of
106.1±4.1
pb
−1
. This paper shows how we have determined the accuracy of our results.
To quantify the risk of using wavelength shifting fiber immersed in pseudocumene-based liquid scintillator, we have measured the rate of reaction of the polystyrene core of this fiber with solutions ...of pseudocumene dissolved in mineral oil. The rate of reaction drops rapidly with concentration. For samples below 17% pseudocumene by volume, the amount of core that reacted in 18 months was less than our measurement limit of
6
μ
m
.
The effects of methods, previously shown to reduce aggression, were determined on the number of aggressive interactions, skin lesions and plasma cortisol concentrations following grouping of four ...unfamiliar, adult ovariectomised pigs. There were four treatments involving 24 pigs in six replicates: (i) Control; (ii) Stall, in which there were four partial stalls used for feeding; (iii) Amperozide, an anti-aggression drug; (iv) Dark in which the pigs were grouped 30 min after sunset. All treatments were in rectangular pens providing a space allowance of 1.4 m
2 per pig. Aggressive interactions were observed for 90 min following grouping and for 40-min periods around feeding on the day following grouping and 9 days later. Skin lesions were assessed 3 days after grouping. The spatial use of the pens was determined during a 60 min period between 14:00 and 16:00 h on the day following grouping and 9 days later. Total cortisol concentrations were determined from samples collected during a 75 min period commencing 90 min and 24 h after the start of grouping and total and free cortisol concentrations were determined from nine blood samples collected at hourly intervals on days 8 and 10.
Fewer aggressive interactions (
P < 0.05) occurred 15–90 min after grouping in the Amperozide and Dark than the Control treatment. The Stall treatment reduced aggressive interactions (
P < 0.05) around feeding on day 10. There were no effects of treatment on the number or length of lesions or the use of the pen during a rest period (
P > 0.05). However, there were significant positive regressions between aggressive interactions and the number and length of lesions (
P < 0.05). There was an acute stress response in the Amperozide treatment 90–165 min after grouping compared with all other treatments (0.001 <
P < 0.01) and the magnitude of this stress response raises some welfare concerns on the use of amperozide. Animals in the Stall treatment showed a lower (
P < 0.01) total cortisol concentration on day 10 than animals in the other treatments and this indicates a welfare benefit from the provision of stalls.
We study D0Dmacr0 pairs produced in e super(+)e super(-)e+e- collisions at s=3.773 GeV using a data sample of 2.92 fb super(-1) collected with the BESIII detector. We measured the asymmetry AK pi CP ...of the branching fractions of D arrow right K super(-) pi super(+)D arrow right K- pi + in CP -odd and CP -even eigenstates to be (12.7 plus or minus 1.3 plus or minus 0.7)10 super(-2)(12.7 plus or minus 1.3 plus or minus 0.7)10-2. AK pi CP can be used to extract the strong phase difference delta sub(K pi ) delta K pi between the doubly Cabibbo-suppressed process Dmacr0 arrow right K- pi + and the Cabibbo-favored process D super(0) arrow right K super(-) pi super(+)D0 arrow right K- pi +. Using world-average values of external parameters, we obtain cos delta K pi =1.02 plus or minus 0.11 plus or minus 0.06 plus or minus 0.01. Here, the first and second uncertainties are statistical and systematic, respectively, while the third uncertainty arises from the external parameters. This is the most precise measurement of delta sub(K pi ) delta K pi to date.
PDF
