Measurements of yields of
13
C(γ,
p
),
14
N(γ, 2
p
), and
14
N(γ, 2
n
) reactions with registration of
12
B and
12
N activities between pulses of the electron accelerator using NaI spectrometers are ...model-considered. The dependence of γ quanta fluxes incident on the target on the thickness of the radiator and angles of collimation is found, along with the efficiency of detecting β particles from
12
B and
12
N decays. The effect of factors related to the diameters of the target and the incident γ beam is evaluated for measuring the yields of the indicated reactions.
K+Λ(1405) photoproduction has been studied at the BGOOD experiment via the all neutral decay, Λ(1405)→Σ0π0. The unique BGOOD experimental setup allows both the cross section and Λ(1405) invariant ...mass distribution (line shape) to be measured over a broad K+ polar angle range, extending to extreme forward K+ angles unattainable at previous experiments.
Evidence is provided for the role of a triangle singularity driven by the N⁎(2030) resonance, which appears to contribute significantly to K+Λ(1405) photoproduction. This is observed in the integrated cross section which was determined with unprecedented energy resolution and supported by the angular distributions. The measured line shape is also in agreement with the previous results of CLAS and ANKE, and is consistent with two poles derived in χPT based models.
The coherent reaction, γd→π0π0d was studied with the BGOOD experiment at ELSA from threshold to a centre-of-mass energy of 2850MeV. A full kinematic reconstruction was made, with final state ...deuterons identified in the forward spectrometer and π0 decays in the central BGO Rugby Ball. The strength of the differential cross section exceeds what can be described by models of coherent photoproduction and instead supports the three isoscalar dibaryon candidates reported by the ELPH collaboration at 2.38, 2.47 and 2.63GeV/c2. A low mass enhancement in the π0π0 invariant mass is also observed at the d⁎(2380) centre-of-mass energy which is consistent with the ABC effect. At higher centre-of-mass energies, a narrow peak in the π0d invariant mass at 2114MeV/c2 with a width of 20MeV/c2 supports a sequential two-dibaryon decay mechanism.
A method for testing threshold SiO
-aerogel Cherenkov detectors using cosmic radiation is described. The implementation requires a minimal amount of additional electronics and does not involve ...massive absorber layers (such as lead, etc.). The method allows for accurate determination of the efficiency of the investigated detectors and for the study of the detectors’ operation in different energy intervals for relativistic particles.
The γp→K+Σ0 differential cross section at extremely forward angles was measured at the BGOOD experiment. A three-quarter drop in strength over a narrow range in energy and a strong dependence on the ...polar angle of the K+ in the centre-of-mass of the reaction is observed at a centre-of-mass energy of 1900 MeV. Residing close to multiple open and hidden strangeness thresholds, the structure appears consistent with meson-baryon threshold effects which may contribute to the reaction mechanism.
Proposed as initial activation experiments for photonuclear research with
-quanta at energies
MeV are those using a source of backward Compton scattered laser radiation on accelerated electrons, ...which is currently under development. These experiments are crucial both for refining the techniques of tuning and monitoring such
-beams, and for investigating the excitation of pygmy and giant resonances in nuclei at
near the threshold of the (
) reactions, as well as the multiplicity of photoneutrons during the de-excitation of E1 giant resonances at
above the threshold of the (
) reactions.
The authors discuss problems of studying the yields of the reactions
13
C(γ,
p
)
12
B,
14
N(γ, 2
p
)
12
B, and
14
N(γ, 2
n
)
12
N with (
12
B,
12
N) activity measured by the telescopes of Δ
E
...detectors in the intervals between electron accelerator pulses. The fluxes and spectra of irradiating bremsstrahlung γ-quanta are found for chosen radiators and targets. The effect the parameters of targets and telescopes of Δ
E
detectors have on the production of (
12
B,
12
N) nuclei and the registration of their decay is estimated.
Conditions are considered that allow the separation of a hypothetical short-lived component (
T
1/2
= 1 ms) in delayed neutrons from
238
U photofission on a pulsed linear electron accelerator when ...neutrons are detected during intervals between beam pulses using a stilbene scintillation spectrometer with pulse shape discrimination of background γ-quanta scintillations.
A study is performed of distortions in the registration of fluxes and energy spectra of delayed neutrons by a stilbene scintillation spectrometer inside Pb shielding. The delayed neutrons are ...products of
238
U photofission on a pulsed electron linear accelerator. The dependences of these distortions on the neutron energy and wall thickness of the Pb shielding are considered. Contributions from processes in the walls of the irradiation hall are described.
In addition to the current BGO-OD experimental program we propose to study nuclear media effects in photoproduction of mesons using a new experimental method based on measuring a recoil nucleon as a ...tagger of the selected partial channel. The principal goal is to learn how unstable mesons (
π
o
, π
+
,
π
−
,
η, ρ, ω
, etc.) interact with nuclear media. This approach continues previous GRAAL experiments to study nuclear excitation dynamics, including multifragmentation of nuclei by intermediate energy photons.
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