Commissioning of the ThomX Storage Ring Kubytskyi, V.; Chaikovska, I.; Delerue, N. ...
Journal of physics. Conference series,
01/2024, Letnik:
2687, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Abstract
We will report on the ongoing ThomX ring commissioning, its status, its main challenges, our results and our planning. ThomX is a compact Compton-based X-ray source under commissioning at ...IJCLab in Orsay (France). This facility is composed of a 50-70 MeV linac, a transfer line and a storage ring whose circumference is 18 m. Compton scattering between the 50 MeV electron bunch of 1 nC and the 30 mJ laser pulses stacked in a Fabry-Perot cavity will result in the production of X-rays with energy ranging between 45 keV and 90 keV. We aim at a total flux of about 10
13
X-rays per second. The injector commissioning started in the spring of 2021. The ongoing storage ring commissioning faces many challenges due to the rings low energy, its compactness, its non-linear beam dynamics, the time-limited beam storage and the need to achieve a very accurate and stable geometry of the collision region between the laser pulses and the electron bunch. The commissioning and operational experience is of great importance for the future Compton sources.
The photoproduction of
95
m
Nb on
nat
Mo
was studied using the electron beam of the LUE-40 linac RDC ”Accelerator” NSC KIPT. Measurements were performed using activation and off-line
γ
-ray ...spectrometric techniques. The experimental flux-averaged cross-section
⟨
σ
(
E
γ
max
)
⟩
m
for the
nat
Mo
(
γ
,
x
n
p
)
95
m
Nb reaction at the bremsstrahlung end-point energy range of 38–93 MeV has been first time obtained. The estimated values
⟨
σ
(
E
γ
max
)
⟩
g
for the formation of
95
Nb in the ground state and total cross-sections
⟨
σ
(
E
γ
max
)
⟩
tot
for the studied reaction were determined. The theoretical values of the yields
Y
m,g,tot
(
E
γ
max
)
and flux-averaged cross-sections
⟨
σ
(
E
γ
max
)
⟩
m
,
g
,
tot
for the
nat
Mo
(
γ
,
x
n
p
)
95
m
,
g
,
t
o
t
Nb reactions were calculated using the cross-sections
σ
(
E
)
from the TALYS1.95 code for six different level density models. The comparison showed a significant excess of the experimental results over the theoretical
⟨
σ
(
E
γ
max
)
⟩
m
,
g
,
tot
values.
Abstract The photoproduction of $$^{95\mathrm m}$$ 95 m Nb on $${^\textrm{nat}\textrm{Mo}}$$ nat Mo was studied using the electron beam of the LUE-40 linac RDC ”Accelerator” NSC KIPT. Measurements ...were performed using activation and off-line $$\gamma $$ γ -ray spectrometric techniques. The experimental flux-averaged cross-section $$\langle {\sigma (E_\mathrm{{\gamma max}})}\rangle _\mathrm{{m}}$$ ⟨ σ ( E γ max ) ⟩ m for the $${^{\textrm{nat}}\textrm{Mo}}(\gamma ,x\mathrm np)^{95\mathrm m}$$ nat Mo ( γ , x n p ) 95 m Nb reaction at the bremsstrahlung end-point energy range of 38–93 MeV has been first time obtained. The estimated values $$\langle {\sigma (E_\mathrm{{\gamma max}})}\rangle _\mathrm{{g}}$$ ⟨ σ ( E γ max ) ⟩ g for the formation of $$^{95}$$ 95 Nb in the ground state and total cross-sections $$\langle {\sigma (E_\mathrm{{\gamma max}})}\rangle _\mathrm{{tot}}$$ ⟨ σ ( E γ max ) ⟩ tot for the studied reaction were determined. The theoretical values of the yields $$Y_\textrm{m,g,tot}(E_\mathrm{{\gamma max}})$$ Y m,g,tot ( E γ max ) and flux-averaged cross-sections $$\langle {\sigma (E_\mathrm{{\gamma max}})}\rangle _\mathrm{{m,g,tot}}$$ ⟨ σ ( E γ max ) ⟩ m , g , tot for the $${^{\textrm{nat}}\textrm{Mo}}(\gamma ,x\mathrm np)^{95\mathrm m,g,tot}$$ nat Mo ( γ , x n p ) 95 m , g , t o t Nb reactions were calculated using the cross-sections $$\sigma (E)$$ σ ( E ) from the TALYS1.95 code for six different level density models. The comparison showed a significant excess of the experimental results over the theoretical $$\langle {\sigma (E_\mathrm{{\gamma max}})}\rangle _\mathrm{{m,g,tot}}$$ ⟨ σ ( E γ max ) ⟩ m , g , tot values.
Abstract
For the Future Circular Collider (FCC-ee), particular attention is drawn to the crucial role of the positron source. Two positron production schemes are considered for the FCC-ee: the ...conventional scheme and the crystal-based (hybrid) scheme that involves channelling radiation in the oriented crystals. A start-to-end simulation toolkit should be developed to design and optimize positron production and capture by considering the positron injector parameters, including the electron drive beam and final system acceptance. This paper presents the first results of benchmarking the FCC-ee positron source simulation tools using the SuperKEKB positron source currently in operation. The model starts with the production of positrons and target studies in Geant4. Then, the RF-Track code is used to capture and track the generated positrons through the capture section composed of a matching device and several accelerating structures embedded in the solenoid field to accelerate the positrons up to 120 MeV. After that, the positrons are further accelerated up to the energy of the Damping Ring (1.1 GeV). Finally, the SuperKEKB capture system is applied to the FCC-ee positron injector within the framework of the design studies.
The flux-averaged cross-sections
⟨
σ
(
E
γ
max
)
⟩
for the
181
Ta
(
γ
,
x
n
;
x
=
1
–
8
)
181
-
x
Ta
reactions have been measured at the end-point bremsstrahlung energies of 80–95 MeV. The ...experiments were performed by using the beam from the NSC KIPT electron linear accelerator LUE-40 and measuring the residual
γ
-ray activities of the reaction products. The theoretical
⟨
σ
(
E
γ
max
)
⟩
values were computed using the mono-energetic cross-sections
σ
(
E
)
from TALYS1.9 code. A comparison between the measured average cross-sections and the theoretical values show good agreement for the
(
γ
,
1
–
6
n
)
reactions but substantial differences for the
(
γ
,
7
n
)
and
(
γ
,
8
n
)
reactions. Isomeric average cross-section ratios
d
(
E
γ
max
)
of a product
178
g
,
m
Ta
produced from the
181
Ta
(
γ
,
3
n
)
reaction have been obtained. The results have been compared with the literature data and the theoretical values based on TALYS1.9 code.
We propose a novel gridless continuous-wave radiofrequency (rf) thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm ...mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.
The paper describes a simulation technique for study of unsteady self-consistent dynamics of charged particles in RF linacs that consist of cavities and travelling wave sections. The approach ...proposed is based on unsteady theories of the excitation of cavities and waveguides by a beam of charged particles and RF feeders. The theory of waveguide excitation is extended to the case of spatially inhomogeneous travelling-wave structures. The SUPERFISH code is used to evaluate the characteristics of the axisymmetric travelling-wave sections. The PARMELA code is applied for simulation of particle motion and to obtain data required for solving the equations for excitation of the RF structures by the beam.
The production of the
180
m
Hf
nuclei in the photoproton reaction
181
Ta
(
γ
,
p
)
was studied at end-point bremsstrahlung energies
E
γ
max
=
35
–95 MeV. The experiment was performed at the electron ...linear accelerator LUE-40 NSC KIPT with the use of the
γ
activation and off-line
γ
-ray spectroscopy. The experimental values of the bremsstrahlung flux-averaged cross-sections
⟨
σ
(
E
γ
max
)
⟩
m
for the
181
Ta
(
γ
,
p
)
180
m
Hf
reaction were determined, and at
E
γ
max
>
55
MeV obtained for the first time. The measured values, as well as the literature data, significantly (by more that an order of magnitude) exceed the theoretical flux-averaged cross-sections
⟨
σ
(
E
γ
max
)
⟩
th
. The
⟨
σ
(
E
γ
max
)
⟩
th
values were calculated using the cross-section
σ
(
E
)
computed with the TALYS1.95 code for six different level density models. A comparative analysis of the calculated total cross-sections from the TALYS computation for the reactions
181
Ta
(
γ
,
p
)
180
Hf
and
181
Ta
(
γ
,
n
)
180
Ta
was performed. It was shown that the photoproton
(
γ
,
p
)
to photoneutron
(
γ
,
n
)
strength ratio is consistent with the estimates based on the isospin selection rules and the value from the
(
e
,
e
′
p
)
experiment.
Abstract
The production of the
$$^{180\textrm{m}}\textrm{Hf}$$
180
m
Hf
nuclei in the photoproton reaction
$${^{181}\textrm{Ta}}(\gamma ,p)$$
181
Ta
(
γ
,
p
)
was studied at end-point bremsstrahlung ...energies
$$E_{\mathrm{\gamma max}}=35$$
E
γ
max
=
35
–95 MeV. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT with the use of the
$$\gamma $$
γ
activation and off-line
$$\gamma $$
γ
-ray spectroscopy. The experimental values of the bremsstrahlung flux-averaged cross-sections
$$\langle {\sigma (E_{\mathrm{\gamma max}})}\rangle _{\textrm{m}}$$
⟨
σ
(
E
γ
max
)
⟩
m
for the
$${^{181}\textrm{Ta}}(\gamma ,p)^{180\textrm{m}}\textrm{Hf}$$
181
Ta
(
γ
,
p
)
180
m
Hf
reaction were determined, and at
$$E_{\mathrm{\gamma max}} > 55$$
E
γ
max
>
55
MeV obtained for the first time. The measured values, as well as the literature data, significantly (by more that an order of magnitude) exceed the theoretical flux-averaged cross-sections
$$\langle {\sigma (E_{\mathrm{\gamma max}})}\rangle _{\textrm{th}}$$
⟨
σ
(
E
γ
max
)
⟩
th
. The
$$\langle {\sigma (E_{\mathrm{\gamma max}})}\rangle _{\textrm{th}}$$
⟨
σ
(
E
γ
max
)
⟩
th
values were calculated using the cross-section
$$\sigma (E)$$
σ
(
E
)
computed with the TALYS1.95 code for six different level density models. A comparative analysis of the calculated total cross-sections from the TALYS computation for the reactions
$${^{181}\textrm{Ta}}(\gamma ,p)^{180}\textrm{Hf}$$
181
Ta
(
γ
,
p
)
180
Hf
and
$${^{181}\textrm{Ta}}(\gamma ,n)^{180}\textrm{Ta}$$
181
Ta
(
γ
,
n
)
180
Ta
was performed. It was shown that the photoproton
$$(\gamma ,p)$$
(
γ
,
p
)
to photoneutron
$$(\gamma ,n)$$
(
γ
,
n
)
strength ratio is consistent with the estimates based on the isospin selection rules and the value from the
$$(e,e'p)$$
(
e
,
e
′
p
)
experiment.
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