A
bstract
The cross section of the process
e
+
e
−
→
π
+
π
−
has been measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2000
e
+
e
−
collider VEPP-2000 in the energy region 525
...<
s
<
883 MeV. The measurement is based on data with an integrated luminosity of about 4.6 pb
−
1
. The systematic uncertainty of the cross section determination is 0.8% at
s
>
0
.
600 GeV. The
ρ
meson parameters are obtained as
m
ρ
= 775
.
3 ± 0
.
5 ± 0
.
6 MeV, Γ
ρ
= 145
.
6 ± 0
.
6 ± 0
.
8 MeV,
B
ρ
→
e
+
e−
×
B
ρ
→
π
+
π−
= (4
.
89 ± 0
.
02 ± 0
.
04) × 10
−
5
, and the parameters of the
e
+
e
−
→
ω
→
π
+
π
−
process, suppressed by
G
-parity, as
B
ω
→
e
+
e−
×
B
ω
→
π
+
π−
= (1
.
32 ± 0
.
06 ± 0
.
02) × 10
−
6
and and
ϕ
ρω
= 110
.
7 ± 1
.
5 ± 1
.
0 degrees.
A technique for measuring the spatial heterogeneity of the light yield of a proton radiography scintillator has been developed. It is based on the recording of digital images formed during the ...passage of a proton beam through a scintillator and the approximation of the intensity distribution in the beam cross section by a two-dimensional Gaussian-like function. The results of the spatial calibration of the light yield of a lutetium silicate scintillator obtained using a magneto-optical proton microscope PUMA are presented. It is shown that accounting of the spatial heterogeneity of the scintillator makes it possible to describe the transverse beam intensity at each point of the proton radiographic image with a mean accuracy of about 0.7%. Experimental data on fluctuations in the position of the beam center, its size, and shape in the scintillator plane of PUMA microscope were obtained. The proposed technique eliminates optical artifacts in the radiographic image caused by operation of the optical recording system and artifacts caused by the electron-optical shutter, provided that the signal is proportional to the intensity of the beam. It also eliminates or strongly suppresses optical artifacts in radiographic images due to changes in the efficiency of a charge-coupled digital camera.
The article describes possible experiments with explosively driven non-ideal plasma at the proton microscope at the Facility for Antiprotons and Ion Research. It is proposed to employ linear ...explosive tubes for plasma generation and to measure an areal density in shock-compressed plasma of argon and xenon. The proposed experiments will provide valuable information on influence of strong interparticle interactions on thermodynamic properties of strongly coupled plasma. The density measurement will help the researchers to understand the nature of wall and wire precursors arising in the shock tubes.
A method has been developed for calculating the proton beam transmission of static objects with a quasi-uniform areal density from a single proton radiography image under the condition of ...a Gaussian-like transverse beam profile. The calculated images of the transmission are intended to reconstruct the density of the investigated objects. A proton radiography of static targets was performed on an experimental setup with special magnetic optics PUMA with a proton energy of 800 MeV and an intensity of 10
10
particles per image. It is shown that the application of the method makes it possible to reconstruct the proton beam transmission of the object under study with an average relative error of approximately 1–1.2%.
The article reviews the design and physical applications of high‐explosive generators for dense low‐temperature plasma. The PUMA proton microscope with magnetic optics at the Institute for ...Theoretical and Experimental Physics by A.I. Alikhanov of National Research Centre «Kurchatov Institute» (Moscow, Russia) was used to diagnose the plasma. The generators were developed for measurements of the equation of state of non‐ideal plasma, investigation of phase transitions in hydrogen or molecular gases, and studies of the properties of the interior of Giant planets. A proposal was made to repeat the experiments with explosive generators using the proton microscope PRIOR (Proton Microscope for Facility for Anti‐proton and Ion Research) at the GSI Helmholtzzentrum fur Schwerionenforschung (Darmstadt, Germany) and at the designed proton microscope at the Institute for Nuclear Research (Troitsk, Russia).
The process
was studied in the energy range between 1 and 2 GeV to the best precision in the world. The data used correspond to an integrated luminosity of
accumulated with the SND detector at the ...VEPP-2000
collider. The statistical accuracy of the measured cross section is 2 to 22
, whereas the systematic uncertainty is 2.6 to 14
. The present results agree with the results of earlier measurements but have a better precision.
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