| 1. |
- Abt, I, et al.
(författare)
-
Inclusive V-0 production cross sections from 920 GeV fixed target proton-nucleus collisions
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 29:2, s. 181-190
-
Tidskriftsartikel (refereegranskat)abstract
- Inclusive differential cross sections dsigma(pA)/dx(F) and dsigma(pA)/dp(t)(2) for the production of K-S(0), Lambda, and (&ULambda;) over bar particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to roots = 41.6 GeV in the proton-nucleon system. The ratios of differential cross sections dsigma(pA)(K-S(0))/dsigma(pA)(Lambda) and dsigma(pA)((&ULambda;) over bar)/dsigma(pA) (Lambda) are measured to be 6.2 +/- 0.5 and 0.66 +/- 0.07, respectively, for x(F) approximate to -0.06. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions da,Ald t also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections sigma(pA) on the atomic mass A of the target material is discussed, and the deduced cross sections per nucleon sigma(pN) are compared with results obtained at other energies.
|
|
| 2. |
- Abt, I, et al.
(författare)
-
Measurement of the b(b)over-bar production cross section in 920 GeV fixed-target proton-nucleus collisions
- 2003
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 26:3, s. 345-355
-
Tidskriftsartikel (refereegranskat)abstract
- Using the HERA-B detector, the b (b) over bar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b (b) over bar production was tagged via inclusive bottom quark decays into J/psi by exploiting the longitudinal separation of J/psi --> l(+)l(-) decay vertices from the primary proton-nucleus interaction. Both e(+)e(-) and mu(+)mu(-) channels have been reconstructed and the combined analysis yields the cross section sigma(b (b) over bar) = 32(-12)(+14)(stat) (+6)(-7)(sys) nb/nucleon.
|
|
| 3. |
- Alcorn, J, et al.
(författare)
-
Basic instrumentation for Hall A at Jefferson Lab
- 2004
-
Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 522:3, s. 294-346
-
Tidskriftsartikel (refereegranskat)abstract
- The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electro-and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. The central components of Hall A are two identical high resolution spectrometers, which allow the vertical drift chambers in the focal plane to provide a momentum resolution of better than 2 x 10(-4). A variety of Cherenkov counters, scintillators and lead-glass calorimeters provide excellent particle identification. The facility has been operated successfully at a luminosity well in excess of 10(38) CM-2 s(-1). The research program is aimed at a variety of subjects, including nucleon structure functions, nucleon form factors and properties of the nuclear medium. (C) 2003 Elsevier B.V. All rights reserved.
|
|
| 4. |
- Dutta, D, et al.
(författare)
-
Nuclear transparency with the gamma n ->pi(-)p process in He-4
- 2003
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 68:2: 021001
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured the nuclear transparency of the fundamental process gamman-->pi(-)p in He-4. These measurements were performed at Jefferson Lab in the photon energy range of 1.6-4.5 GeV and at theta(cm)(pi)=70degrees and 90degrees. These measurements are the first of their kind in the study of nuclear transparency in photoreactions. They also provide a benchmark test of Glauber calculations based on traditional models of nuclear physics. The transparency results suggest deviations from the traditional nuclear physics picture. The momentum transfer dependence of the measured nuclear transparency is consistent with Glauber calculations that include the quantum chromodynamics phenomenon of color transparency.
|
|
| 5. |
- Zhu, LY, et al.
(författare)
-
Cross-section measurement of charged-pion photoproduction from hydrogen and deuterium
- 2003
-
Ingår i: Physical Review Letters. - 1079-7114. ; 91:2: 022003
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured the differential cross section for the gamman-->pi(-)p and gammap-->pi(+)n reactions at theta(c.m.)=90degrees in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at E(gamma)greater than or similar to3.3 GeV exhibit a global scaling behavior for both pi(-) and pi(+) photoproduction, consistent with the constituent counting rule and the existing pi(+) photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi(-) to pi(+) photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams.
|
|
| 6. |
- Ma, W. C., et al.
(författare)
-
Competition between terminating and collective structures above spin 40ℏ in 154Dy
- 2002
-
Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 65, s. 1-034312
-
Tidskriftsartikel (refereegranskat)abstract
- High-spin states in 154Dy were studied with the Gammasphere spectrometer using the 36S(122Sn,4n) reaction. Band terminating states were identified in the spin range I= (36-48)ℏ, and were found to compete with collective rotational cascades up to the highest observed spins. Several "sidebands" feeding the terminating structures were identified as well. A band dominated by M1 transitions was observed to terminate at Iπ = 42-. The data are interpreted within the framework of configuration-dependent cranked Nilsson-Strutinsky calculations without pairing.
|
|
| 7. |
|
|
| 8. |
- Zhu, Bin, et al.
(författare)
-
Innovative low temperature SOFCs and advanced materials
- 2003
-
Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 118:02-jan, s. 47-53
-
Tidskriftsartikel (refereegranskat)abstract
- High ionic conductivity, varying from 0.01 to 1 S cm(-1) between 300 and 700 degreesC, has been achieved for the hybrid and nano-ceriacomposite electrolyte materials, demonstrating a successful application for advanced low temperature solid oxide fuel cells (LTSOFCs). The LTSOFCs were constructed based on these new materials. The performance of 0.15-0.25 W cm(-2) was obtained in temperature region of 320400 degreesC for the ceria-carbonate composite electrolyte, and of 0.35-0.66 W cm(-2) in temperature region of 500-600 degreesC for the ceria-lanthanum oxide composites. The cell could even function at as low as 200 degreesC. The cell has also undergone a life test for several months. A two-cell stack was studied, showing expected performance successfully. The excellent LTSOFC performance is resulted from both functional electrolyte and electrode materials. The electrolytes are two phase composite materials based on the oxygen ion and proton conducting phases, or two rare-earth oxides. The electrodes used were based on the same composite material system having excellent compatibility with the electrolyte. They are highly catalytic and conductive thus creating the excellent performances at low temperatures. These innovative LT materials and LTSOFC technologies would open the door for wide applications, not only for stationary but also for mobile power sources.
|
|
| 9. |
- Zhu, J. W., et al.
(författare)
-
Identification of (Z)-4-tridecene from defensive secretion of green lacewing, Chrysoperla carnea
- 2000
-
Ingår i: Journal of Chemical Ecology. - : Springer. - 0098-0331 .- 1573-1561. ; 26:10, s. 2421-2434
-
Tidskriftsartikel (refereegranskat)abstract
- We report the identification of a defensive secretion from the green lacewing, Chrysoperla carnea. By using combined gas chromatography-electroantennographic detection (GC-EAD), we found one major compound in the solvent extract of this secretion that elicited a significant EAD response from the antenna. Based upon its characteristic fragments from gas chromatography-mass spectrometry (GC-MS) analysis, the compound was identified as a tridecene. Dimethyldisulfide derivatization suggested that a double bond was located between positions 4 and 5 in the carbon chain. Thus, the compound was tentatively identified as a 4-tridecene. Coinjection of the extract with a mixture of the Z or E form of the synthetic 4-tridecene revealed that the unknown was (Z)-4-tridecene. EAG dose-responses showed a direct correlation to dose. Single sensillum recordings from sensilla trichodea situated on the antennae suggested the presence of receptor neurons specifically responding to this compound. An arrestment behavior was observed when tested in the Y-tube olfactometer. Preliminary field trapping results indicate that the compound is an antagonist to attraction. The avoidance behavior of predatory ants, observed when tested with the synthetic compound of this secretion further suggested a defensive function.
|
|
| 10. |
|
|
