The Belle II detector at the Super KEKB e+e−collider plans to take first collision data in 2018. The monetary and CPU time costs associated with storing and processing the data mean that it is ...crucial for the detector components at Belle II to be calibrated quickly and accurately. A fast and accurate calibration system would allow the high level trigger to increase the efficiency of event selection, and can give users analysis-quality reconstruction promptly. A flexible framework to automate the fast production of calibration constants is being developed in the Belle II Analysis Software Framework (basf2). Detector experts only need to create two components from C++ base classes in order to use the automation system. The first collects data from Belle II event data files and outputs much smaller files to pass to the second component. This runs the main calibration algorithm to produce calibration constants ready for upload into the conditions database. A Python framework coordinates the input files, order of processing, and submission of jobs. Splitting the operation into collection and algorithm processing stages allows the framework to optionally parallelize the collection stage on a batch system.
The cross section for inclusive multipion production in the pp-->ppX reaction was measured at COSY-ANKE at four beam energies, 0.8, 1.1, 1.4, and 2.0 GeV, for low excitation energy in the final pp ...system, such that the diproton quasiparticle is in the 1S0 state. At the three higher energies, the missing-mass M_{X} spectra show a strong enhancement at low M_{X}, corresponding to an Abashian-Booth-Crowe effect that moves steadily to larger values as the energy is increased. Despite the missing-mass structure looking very different at 0.8 GeV, the variation with M_{X} and beam energy are consistent with two-pion production being mediated through the excitation of two Delta(1232) isobars, coupled to S and D states of the initial pp system. There is no sign of any resonancelike structure in the energy dependence of the type recently observed for the pn-->dpi;{0}pi;{0} total cross section.
The HERMES experiment at DESY, Hamburg, collected unique data on Deeply Virtual Compton Scattering (DVCS) utilizing the HERA polarized electron or positron beams with an energy of 27.6 GeV and ...longitudinally or transversely polarized or unpolarized gas targets (H, D or heavier nuclei). For the last two years of HERA running, a recoil detector was installed to improve the selection of DVCS events by direct measurement of the recoil protons. Recent HERMES results on DVCS off the hydrogen target and on associated processes
ep
→
ep
π
0
γ and
ep
→
en
π
+
γ in the Δ-resonance region obtained with the recoil detector are presented.
The vector and tensor polarizations of a deuteron beam have been measured using elastic deuteron-carbon scattering at 75.6 MeV and deuteron-proton scattering at 270 MeV. After their acceleration to ...1170 MeV inside the COSY ring, the polarizations of the deuterons were checked by studying a variety of nuclear reactions using a cluster target at the ANKE magnet spectrometer placed at an internal target position of the storage ring. All these measurements were consistent with the absence of depolarization during acceleration and provide us with a number of secondary standards that can be used in subsequent experiments at the facility.
A
bstract
A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized ...protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing cos (
ϕ−ϕ
S
) modulations provide evidence for a sizable worm-gear (II) distribution,
g
1
T
q
x
p
T
2
. Most of the other modulations are found to be consistent with zero with the notable exception of large sin (
ϕ
S
) modulations for charged pions and
K
+
.
Azimuthal single-spin asymmetries of leptoproduced pions and charged kaons were measured on a transversely polarized hydrogen target. Evidence for a naive-T-odd, transverse-momentum-dependent parton ...distribution function is deduced from nonvanishing Sivers effects for pi(+), pi(0), and K(+/-), as well as in the difference of the pi(+) and pi(-) cross sections.
A study of the deuteron breakup reaction pd→(pp)n with forward emission of a fast proton pair with small excitation energy Epp< 3 MeV has been performed using the ANKE spectrometer at COSY-Jülich. An ...exclusive measurement was carried out at six proton-beam energies Tp= 0.6, 0.7, 0.8, 0.95, 1.35 and 1.9 GeV by reconstructing the momenta of the two protons. The differential cross section of the breakup reaction, averaged up to 8° over the cm polar angle of the total momentum of the pp pairs, has been obtained. Since the kinematics of this process is quite similar to that of backward elastic pd→dp scattering, the results are compared to calculations based on a theoretical model previously applied to the pd→dp process.
A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen ...and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously.
Constrained minimization in the C++ environment Dymov, S.N; Kurbatov, V.S; Silin, I.N ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2000, Letnik:
440, Številka:
2
Journal Article
Recenzirano
On the basis of the ideas, proposed by one of the authors (I.N. Silin), a suitable software has been developed for constrained data fitting. Constraints may be of arbitrary type; i.e. equalities and ...inequalities. The simplest possible way has been used. The widely known program FUMILI was re-written in the C++ language. Constraints in the form of inequalities
φ(
θ)≥a
were taken into account by changing them into equalities
φ(
θ)=t
and simple inequalities of type
t≥
a. The equalities were taken into account by means of quadratic penalty functions. The suitable software was tested on the model data for the ANKE setup (COSY accelerator, Forschungszentrum Jülich, Germany).
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