The LHC Phase II Upgrade foreseen for 2026 implies multi fold increasing of number of collisions and radiation levels compared to the present LHC conditions. The electromagnetic calorimeter (ECAL) of ...LHCb experiment requires modernization due to enlarged radiation doses and high occupancy: replacing shashlik-type modules for the central part by spaghetti-type (SPACAL) calorimeter. Current paper presents results of the material optimization (fiber diameter and distance between their centers (pitch), absorber material) for lead-polystyrene SPACAL module performed with GEANT4 simulation to satisfy the LHCb requirements in terms of energy resolution.
Geant4 based simulation study of energy resolution is performed for Spaghetti electromagnetic calorimeter module (SPACAL). Several configurations of SPACAL module, with different fiber pitch and ...scintillation material, were simulated. For each configuration, the energy and angular dependencies of energy resolution were determined. The sampling fraction for electromagnetic showers for the selected SPACAL configuration was also determined
Performance parameters of a composite detection module of Spaghetti type Calorimeter (SPACAL), which is considered for the inner part of the future LHCb Electromagnetic Calorimeter (ECAL) in Upgrade ...Phase 2, are simulated using GEANT4 software supported by analytical calculations. The accuracy of the timestamp is estimated in both the front and back sections of the composite detector, whereas the energy resolution is estimated for the total signal from the front and back sections of the detector. The rise time of the scintillation response used in the calculations is reconstructed using the results of the coincidence time resolution measurements with annihilation γ-quanta. The time and energy resolutions with PMT readout are compared for Ce-doped garnet- and oxyorthosilicate-type single crystal scintillators without codoping and codoped with aliovalent impurities.
Results of developing of a gamma-ray detector based on LaBr3(Ce) scintillation crystal for neutron capture therapy are presented. An energy resolution of the detector measured by photomultiplier tube ...Hamamatsu R6233-100 is showed. It was 2.93% for gamma line 662 keV from a source 137Cs. For radiative capture gamma line of isotope 10B (478 keV) and annihilation line (511 keV) the values were 3.33 and 3.24% respectively. Data analysis of gamma spectra for an estimation of energy resolution threshold required for visual identification gamma lines 478 and 511 keV was made.
Irradiation studies of a multi-doped Gd3Al2Ga3O12 scintillator Alenkov, V.; Buzanov, O.; Dosovitskiy, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2019, Letnik:
916
Journal Article
Recenzirano
Odprti dostop
The characteristics of a Gd3Al2Ga3O12 crystal scintillator doped with cerium and co-doped with magnesium and titanium have been studied, mainly in view of using it for the Phase II upgrade of the ...LHCb electromagnetic calorimeter. Samples of the scintillator were irradiated with γ (60Co) to 2 kGy and with 24 GeV protons to 900 kGy. The proton fluence value was ∼3⋅1015cm−2. It was found that γ-irradiation did not produce any change in the optical transmission of the crystals in the spectral range of the scintillation light, whereas a degradation after the proton irradiation was measurable. For the 1 cm thick sample, a loss of transmission of 3.6% was measured at the wavelength of maximum scintillation (520 nm), and the measured induced absorption coefficient at this wavelength was ∼3.6 m−1. The formation of radioisotopes in the crystal at proton irradiation has been analysed. The formation of isotopes was also simulated with the help of the FLUKA package. The simulation was found to be in a good agreement with experimental results. The results have been used to estimate the expected intensity of parasitic radio-luminescence at high-luminosity operation in a GAGG/W sampling electromagnetic calorimeter.
A spaghetti calorimeter (SPACAL) prototype with scintillating crystal fibres was assembled and tested with electron beams of energy from 1 to 5 GeV. The prototype comprised radiation-hard ...Cerium-doped Gd3Al2Ga3O12 (GAGG:Ce) and Y3Al5O12 (YAG:Ce) embedded in a pure tungsten absorber. The energy resolution was studied as a function of the incidence angle of the beam and found to be of the order of 10%/E⊕1%, in line with the LHCb Shashlik technology. The time resolution was measured with metal channel dynode photomultipliers placed in contact with the fibres or coupled via a light guide, additionally testing an optical tape to glue the components. Time resolution of a few tens of picosecond was achieved for all the energies reaching down to (18.5 ± 0.2) ps at 5 GeV.
Abstract The decays B+ → J/ψπ+π − K+ are studied using a data set corresponding to an integrated luminosity of 9 fb −1 collected with the LHCb detector in proton-proton collisions between 2011 and ...2018. Precise measurements of the ratios of branching fractions with the intermediate ψ2(3823), χc1(3872) and ψ(2S) states are reported. The values are B B + → ψ 2 3823 K + × B ψ 2 3823 → J / ψπ + π − B B + → χ c 1 3872 K + × B χ c 1 3872 → J / ψπ + π − = 3.56 ± 0.67 ± 0.11 × 10 − 2 , B B + → ψ 2 3823 K + × B ψ 2 3823 → J / ψπ + π − B B + → ψ 2 S K + × B ψ 2 S → J / ψπ + π − = 1.31 ± 0.25 ± 0.04 × 10 − 3 , B B + → χ c 1 3872 K + × B χ c 1 3872 → J / ψπ + π − B B + → ψ 2 S K + × B ψ 2 S → J / ψπ + π − = 3.69 ± 0.07 ± 0.06 × 10 − 2 , $$ {\displaystyle \begin{array}{c}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\upchi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(3.56\pm 0.67\pm 0.11\right)\times {10}^{-2},\\ {}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\uppsi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi_2(3823)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \uppsi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(1.31\pm 0.25\pm 0.04\right)\times {10}^{-3},\\ {}\frac{{\mathcal{B}}_{\mathrm{B}+\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\upchi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \uppsi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/{\uppsi \uppi}^{+}{\uppi}^{-}}}=\left(3.69\pm 0.07\pm 0.06\right)\times {10}^{-2},\end{array}} $$ where the first uncertainty is statistical and the second is systematic. The decay of B+ → ψ2(3823)K+ with ψ2(3823) → J/ψπ+π − is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ2(3823), χc1(3872) and ψ(2S) states are measured to be m χ c 1 3872 − m ψ 2 3823 = 47.50 ± 0.53 ± 0.13 MeV / c 2 , m ψ 2 3823 − m ψ 2 2 S = 137.98 ± 0.53 ± 0.14 MeV / c 2 , m χ c 1 3872 − m ψ 2 2 S = 185.49 ± 0.06 ± 0.03 MeV / c 2 , $$ {\displaystyle \begin{array}{c}{m}_{\upchi_{\mathrm{c}1}(3872)}-{m}_{\uppsi_2(3823)}=47.50\pm 0.53\pm 0.13\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\uppsi_2(3823)}-{m}_{\uppsi_2\left(2\mathrm{S}\right)}=137.98\pm 0.53\pm 0.14\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\upchi_{\mathrm{c}1}(3872)}-{m}_{\uppsi_2\left(2\mathrm{S}\right)}=185.49\pm 0.06\pm 0.03\;\mathrm{MeV}/{c}^2,\end{array}} $$ resulting in the most precise determination of the χc1(3872) mass. The width of the ψ2(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χc1(3872) state is measured to be Γ χ c 1 3872 BW = 0.96 − 0.18 + 0.19 ± 0.21 MeV $$ {\Gamma}_{\upchi_{\mathrm{c}1}(3872)}^{\mathrm{BW}}={0.96}_{-0.18}^{+0.19}\pm 0.21\;\mathrm{MeV} $$ which is inconsistent with zero by 5.5 standard deviations.
A
bstract
Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb
−1
, collected with the LHCb detector between 2011 and 2018, a new narrow charmonium state, the X(3842) ...resonance, is observed in the decay modes
$$ \mathrm{X}(3842)\to {D}^0{\overline{D}}^0 $$
X
3842
→
D
0
D
¯
0
and X(3842) →
D
+
D
−
. The mass and the natural width of this state are measured to be
$$ \begin{array}{l}{m}_{X(3842)}=3842.71\pm 0.16\pm 0.12\ MeV/{c}^2,\hfill \\ {}{\varGamma}_{X(3842)}=2.79\pm 0.51\pm 0.35\ MeV,\hfill \end{array} $$
m
X
3842
=
3842.71
±
0.16
±
0.12
M
e
V
/
c
2
,
Γ
X
3842
=
2.79
±
0.51
±
0.35
M
e
V
,
where the first uncertainty is statistical and the second is systematic. The observed mass and narrow natural width suggest the interpretation of the new state as the unobserved (spin-3
ψ
3
1
3
D
3
) charmonium state.
In addition, prompt hadroproduction of the
ψ
(3770) and
χ
2
(3930) states is observed for the first time, and the parameters of these states are measured to be
$$ \begin{array}{l}{m}_{\psi (3770)}=3778.1\pm 0.7\pm 0.6\ MeV/{c}^2,\hfill \\ {}{m}_{\chi_2(3930)}=3921.9\pm 0.6\pm 0.2\ MeV/{c}^2,\hfill \\ {}{\varGamma}_{\chi_2(3930)}=36.6 \pm 1.9 \pm 0.9\ MeV,\hfill \end{array} $$
m
ψ
3770
=
3778.1
±
0.7
±
0.6
M
e
V
/
c
2
,
m
χ
2
3930
=
3921.9
±
0.6
±
0.2
M
e
V
/
c
2
,
Γ
χ
2
3930
=
36.6
±
1.9
±
0.9
M
e
V
,
where the first uncertainty is statistical and the second is systematic.
Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb(-1) collected with the LHCb detector, seven decay modes of the B-C(+) meson into a J/psi or psi(2S) meson and ...three charged hadrons, kaons or pions, are studied. The decays B-C (+)-> (psi(2S) -> J/psi pi(+)pi(-))pi(+), B+C -> (psi(2S)pi(+)pi(-)pi(+), B+C -> J/psi K+pi(-)pi(+) and B+C -> J/K+K-K+ are observed for the first time, and evidence for the B-C (+)-> (psi(2S)K+K-pi(+), decay is found, where J/psi and psi(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different B-C(+) decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.
Irradiation studies of a multi-doped Gd 3 Al 2 Ga 3 O12 scintillator Alenkov, V.; Buzanov, O.; Dosovitskiy, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2019, Letnik:
916
Journal Article
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