Ultra-thin gas detector for tracking of low energy electrons Lojek, K.; Bodek, K.; Kuzniak, M.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2009, Letnik:
611, Številka:
2
Journal Article
Recenzirano
The paper presents the most important results of a study performed with a prototype multiwire drift chamber (MWDC) operated with helium at
100
–
1000
mbar
pressure with only
10
–
30
%
isobutane ...admixture. At certain conditions, a spatial resolution better than
500
μ
m
and an efficiency higher than 95% were achieved. Such detectors are well suited for beta decay correlation experiments. Possibly they could be advantageous as monitors of backscattering from electron energy detectors and as ion cloud size monitors in ion traps.
The two transverse polarization components P(T1) and P(T2) of the e(+) from the decay of polarized mu(+) have been measured as a function of the e(+) energy. Their energy averaged values are ...P(T1)=(6.3+/-7.7+/-3.4) x 10(-3) and P(T2)=(-3.7+/-7.7+/-3.4) x 10(-3). From the energy dependence of P(T1) and P(T2) the decay parameters eta,eta('') and alpha(')/A,beta(')/A are derived, respectively. Assuming only one additional coupling besides the dominant V-A interaction one gets improved limits on eta, beta(')/A, and the scalar coupling constant g(S)(RR): eta=(-2.1+/-7.0+/-1.0) x 10(-3), beta(')/A=(-1.3+/-3.5+/-0.6) x 10(-3), Re{g(S)(RR)}=(-4.2+/-14.0+/-2.0) x 10(-3), and Im{g(S)(RR)}=(5.2+/-14.0+/-2.4) x 10(-3).
The aim of the present study was the evaluation of basic fibroblast growth factor (bFGF, FGF-2) release in vitro from four types of polymer bases (carriers), fibrin, microcrystalline chitosan (MCCh), ...fibrin and MCCh, as well as MCCh and methylcellulose (MC) in the presence or absence of ketoprofen (KTA). Amount of released basic fibroblast growth factor was measured immunoenzymatically using Elisa (R&D System). Ketoprofen concentration was determined spectrophoto-metrically at 255 nm, using an appropriate absorbance factor, alpha 1 cm (1%) = 662. The most significant influence of ketoprofen on bFGF release was seen in the case of microcrystalline chitosan carrier elution. Parameters of the equation which describe the amount of bFGF released from chitosan carrier with and without KTA are y = 6.842 +/- 1.637 In(t) + 14.935 +/- 2.378, determination coefficient, R2 = 0.9332 and y = 4.070 +/- 0.622 In(t) + 10.589 +/- 1.011, determination coefficient, R2 = 0.9606. The time after which 20% of bFGF was released (t 20%) in the presence of ketoprofen was 2.1 h whereas it was significantly longer without ketoprofen (10.1 h). The amount of bFGF released from fibrin carrier was lower in the presence of ketoprofen. The time taken for 20% of bFGF to be released (t 20%) was very long (41.7h) in the presence of KTA and 16.3 h. without KTA. The other carriers (fibrin + MCCh and MCCh + MC) in the presence of ketoprofen appear to have an insignificant influence on the kinetics of basic fibroblast growth factor release. For the chitosan carrier (p = 0.05, and also p = 0.01, when t(theoret) = 2.921), there is a statistically significant difference between the coefficients (a1 and a2) of the regression equation describing the process of basic fibroblast growth factor release from the base with and without ketoprofen. It was also found that the amount of ketoprofen released varied considerably according to the carrier. All results clearly indicate that the type of carrier not only has an impact on the amount of bFGF released, but also on the kinetics of ketoprofen release.
An analytic solution to the magnetostatic inverse problem in the framework of vector spherical harmonic basis functions is presented. This formalism is used for the design of a spherical magnetic ...field compensation system and its performance is compared with an already existing rectangular coil system. The proposed set of spherical coils with 15 degrees of freedom achieves a shielding factor of 1000 or better in a large part of the volume enclosed by the coils for a dipolar type external perturbation.
A set of differential cross-section data of the
1
H
(
d
, pp)n breakup reaction at 130 MeV deuteron beam energy has been measured in the domain of very forward polar angles with the use of the ...Germanium Wall detector at the Forschungszentrum Jülich. The data obtained for over 1000 kinematical points (112 geometries) are compared with the theoretical predictions based on various models of the three-nucleon (3N) dynamics. They comprise: the realistic nucleon-nucleon potentials alone or combined with the three-nucleon force (3NF), the coupled-channel calculations with the explicit treatment of the
Δ
-isobar excitation and finally, the potentials derived from chiral perturbation theory. In the part of the phase space studied, the Coulomb interaction between protons has a strong impact on the differential cross section of the breakup reaction. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest. In these regions the data are well reproduced exclusively by calculations which include the electromagnetic repulsion between protons. In spite of the dominance of the Coulomb force in the phase space studied, the contribution of 3NF effects is also observed.
The neutron gyromagnetic ratio has been measured relative to that of the 199Hg atom with an uncertainty of 0.8 ppm. We employed an apparatus where ultracold neutrons and mercury atoms are stored in ...the same volume and report the result γn/γHg=3.8424574(30).
The total scattering cross sections for slow neutrons with energies in the range 100 neV to 3 meV for solid ortho-2H2 at 18 and 5 K, frozen from the liquid, have been measured. The 18 K cross ...sections are found to be in excellent agreement with theoretical expectations and for ultracold neutrons dominated by thermal up scattering. At 5 K the total scattering cross sections are found to be dominated by the crystal defects originating in temperature induced stress but not deteriorated by temperature cycles between 5 and 10 K.
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