Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, ...FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
The nuclear medium influence on the dihadron neutrino charged current production is investigated using the data obtained with SKAT bubble chamber. An indication is obtained that the nuclear ...attenuation of the dihadron production is more expressed for kinematically closest hadron pairs. The experimental data are compared with predictions of the string model.
The production of charged
ρ
mesons on nuclei and nucleons is investigated in charged current neutrino interactions at moderate energies (〈
E
〉
≈ 10 GeV), using the data obtained with SKAT bubble ...chamber. No strong nuclear effects are observed in
ρ
+
and
ρ
−
production. The fractions of charged and neutral pions originating from
ρ
decays are obtained and compared with higher-energy data. From analysis of the obtained and available data on
ρ
+
and
K
*
+
(892) neutrino production, the strangeness suppression factor is extracted:
λ
s
= 0.18 ± 0.03. Estimation is obtained for cross section of coherent
ρ
+
neutrino production on nuclei.
The charged current neutrino production of {phi} and D{sub s}{sup +} mesons is studied, using the data obtained with the SKAT bubble chamber exposed to the Serpukhov accelerator neutrino beam. It is ...found that the {phi} production occurs predominantly in the forward hemisphere of the hadronic c.m.s. (at x{sub F} > 0, x{sub F} being the Feynman variable), with the mean yield strongly exceeding the expected yield of directly produced {phi} mesons and varying from Left-Pointing-Angle-Bracket n{sub {phi}}(x{sub F} s 0) Right-Pointing-Angle-Bracket = (0.92 {+-} 0.34) Multiplication-Sign 10{sup -2} at W > 2 GeV up to (1.23 {+-} 0.53) Multiplication-Sign 10{sup -2} at W > 2.6 GeV and (1.44 {+-} 0.69) Multiplication-Sign 10{sup -2} at W > 2.9 GeV, W being the invariant mass of the hadronic system. For the first time, the inclusive yield of leading D{sub s}{sup +} mesons carrying more than z = 0.85 of the current c-quark energy is estimated: Left-Pointing-Angle-Bracket n{sub Ds}{sup +}(z > 0.85, W > 2.9 GeV) Right-Pointing-Angle-Bracket = (6.64 {+-} 1.91) Multiplication-Sign 10{sup -2}. It is shown that the shape of measured {phi} meson differential spectrum on xF is reproduced by that expected from the D{sub s}{sup +} {yields} {phi}X decays. An indication was obtained that this expected spectrum underestimates the measured {phi} yield.
The production of charged {rho} mesons on nuclei and nucleons is investigated in charged current neutrino interactions at moderate energies (<E{sub >} Almost-Equal-To 10 GeV), using the data obtained ...with SKAT bubble chamber. No strong nuclear effects are observed in {rho}{sup +} and {rho}{sup -} production. The fractions of charged and neutral pions originating from {rho} decays are obtained and compared with higher-energy data. From analysis of the obtained and available data on {rho}{sup +} and K*{sup +}(892) neutrino production, the strangeness suppression factor is extracted: {lambda}{sub s} = 0.18 {+-} 0.03. Estimation is obtained for cross section of coherent {rho}{sup +} neutrino production on nuclei.
The total yields of the all well established light meson resonances (up to the {phi}(1020) meson) are estimated in neutrino-nucleus charged current interactions at Left-Pointing-Angle-Bracket E{sub ...{nu}} Right-Pointing-Angle-Bracket Almost-Equal-To 10 GeV, using the data obtained with SKAT bubble chamber. The yield of {phi} meson in neutrino production is obtained for the first time. For some resonances, the yields in the forward and backward hemispheres in the hadronic c.m.s. are also extracted. From the comparison of the obtained and available higher-energy data, an indication is obtained that the resonance yields rise almost linearly as a function of the mass W of the neutrino produced hadronic system. The fractions of pions originating from the light resonance decays are inferred.
The charged current neutrino production of
φ
and
D
s
+
mesons is studied, using the data obtained with the SKAT bubble chamber exposed to the Serpukhov accelerator neutrino beam. It is found that the
...φ
production occurs predominantly in the forward hemisphere of the hadronic c.m.s. (at
x
F
> 0,
x
F
being the Feynman variable), with the mean yield strongly exceeding the expected yield of directly produced
φ
mesons and varying from 〈
n
φ
(
x
F
s 0)〉 = (0.92 ± 0.34) × 10
−2
at
W
> 2 GeV up to (1.23 ± 0.53) × 10
−2
at
W
> 2.6 GeV and (1.44 ± 0.69) × 10
−2
at
W
> 2.9 GeV,
W
being the invariant mass of the hadronic system. For the first time, the inclusive yield of leading
D
s
+
mesons carrying more than
z
= 0.85 of the current
c
-quark energy is estimated: 〈
n
D
s
+
(
z
> 0.85,
W
> 2.9 GeV)〉 = (6.64 ± 1.91) × 10
−2
. It is shown that the shape of measured
φ
meson differential spectrum on
x
F is reproduced by that expected from the
D
s
+
→
φX
decays. An indication was obtained that this expected spectrum underestimates the measured
φ
yield.
The total yields of the all well established light meson resonances (up to the
ϕ
(1020) meson) are estimated in neutrino-nucleus charged current interactions at 〈
E
ν
〉 ≈ 10 GeV, using the data ...obtained with SKAT bubble chamber. The yield of
ϕ
meson in neutrino production is obtained for the first time. For some resonances, the yields in the forward and backward hemispheres in the hadronic c.m.s. are also extracted. From the comparison of the obtained and available higher-energy data, an indication is obtained that the resonance yields rise almost linearly as a function of the mass
W
of the neutrino produced hadronic system. The fractions of pions originating from the light resonance decays are inferred.
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