Ren-Yuan Zhu

This paper presents new developments in inorganic scintillators widely used for radiation detection. It addresses major emerging research topics outlining current needs for applications and material sciences issues with the overall aim to provide an up-to-date picture of the field. While the traditional forms of scintillators have been crystals and ceramics, new research on films, nanoparticles, and microstructured materials is discussed as these material forms can bring new functionality and therefore find applications in radiation detection. The last part of the contribution reports on the very recent evolutions of the most advanced theories, methods, and analyses to describe the scintillation mechanisms.

This paper presents a comparative study of optical and scintillation properties for various inorganic crystal scintillators, which are used, or actively pursued, by the high energy physics community for experiments. Transmittance, excitation and photo-luminescence spectra were measured for samples with a dimension of 1.5 radiation length. The transmittance data are compared to the theoretical limit calculated by using refractive index, assuming no internal absorption. Refractive index of lutetium oxyorthosilicate and lutetium-yttrium oxyorthosilicate was measured by using a V-prism. Light output was measured for these samples with Tyvek paper wrapping, and the result is presented with the quantum efficiency of the readout devices taken out. Temperature coefficient of the light output was also measured. The result of these measurements will be used in the summary table of the inorganic scintillator section for the 2008 edition of the particle data book.

Measurements of the reactions ${e}^{+}+{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}+{e}^{\ensuremath{-}}$, ${\ensuremath{\mu}}^{+}+{\ensuremath{\mu}}^{\ensuremath{-}}$, and ${\ensuremath{\tau}}^{+}+{\ensuremath{\tau}}^{\ensuremath{-}}$ at PETRA energies (${s}^{\frac{1}{2}}=13,17,27.4,30 \mathrm{and} 31.6$ GeV) are reported. The results show that these reactions agree well with the predictions of quantum electrodynamics thus determining that all the known charged leptons are pointlike particles to a distance \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}16}$ cm.

PETRA, the e+e− collider, has operated at a maximum CM energy of 46.78 GeV. We update our previous results on new particle searches and set significantly better mass limits on some.

Following our previous studies, a further investigation on three long (2.5 times 2.5 times 20 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) LSO and LYSO crystal samples was carried out, and was compared to a long BGO sample of the same size. The optical and scintillation properties, including transmittance, photo-luminescence and excitation spectra, were measured. The result of light output and light response uniformity, measured by using both PMT and APD, are reported. Their applications in future high energy physics experiments are discussed.

We report on the multiple wavelength laser monitoring system designed for the compact muon solenoid (CMS) lead tungstate crystal calorimeter. Results are presented for the test-beam performance of the system designed to achieve ⩽0.2% relative optical transmittance inter-calibration for 75 848 lead tungstate crystals. The system cycles continuously over the calorimeter to follow each crystal's evolution under the irradiation and recovery periods foreseen during operation at the LHC.

The results of a high-statistics study of inclusive muon spectra at PETRA are reported.Improved mass limits have been obtained for heavy quarks, heavy leptons, and charged Higgs particles.It is shown that the fragmentation properties of b quarks and c quarks

Because of their high stopping power (X 0 = 1.14 cm), fast (τ = 40 ns) bright (4 times BGO) scintillation with small temperature coefficient (−0.2%/°C) and superb radiation hardness, LSO/LYSO crystals are chosen to construct electromagnetic calorimeters (ECAL) of total absorption nature. One critical issue for this application is the light response uniformity (LRU) of long crystal bars with tapered geometry, which is affected by the non-uniform light yield along the crystal, the self-absorption and the optical focusing effect. Following a ray-tracing simulation study, an uniformization method was developed by roughening one side surface with LRU of better than 3% achieved. LSO/LYSO crystals are also proposed as the active material for a sampling ECAL for future HEP experiments in severe radiation environment. Preliminary designs with Pb or W absorber are described. Measurements of light collection efficiency (LCE) for prototype Shashlik cells with wavelength shifting fiber readout are presented. Future development on LSO/LYSO crystal based sampling ECAL is discussed.

Because of their superb energy resolution and detection efficiency scintillation crystals are widely used in high energy and nuclear physics experiments. A crucial issue is radiation damage in crystals. We report an investigation on γ-ray induced radiation damage in various crystal scintillators of large size, including BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , BGO, CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , pure CsI, LSO/LYSO/LFS and PWO, with an integrated dose up to 340 Mrad and a dose rate up to 1 Mrad/h. Optical and scintillation properties of these crystal samples were measured before and after irradiations. The results show that pure CsI has good radiation hardness below 100 krad. BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , BGO and LYSO have good radiation hardness beyond 1 Mrad. In terms of light output degradation LYSO is clearly the best among all scintillation crystals.

Crystal detectors have been used widely in high energy and nuclear physics experiments, medical instruments and homeland security applications. Novel crystal detectors are continuously being discovered and developed in academia and in industry. In high energy and nuclear physics experiments, total absorption electromagnetic calorimeters (ECAL) made of inorganic crystals are known for their superb energy resolution and detection efficiency for photon and electron measurements. A crystal ECAL is thus the choice for those experiments where precision measurements of photons and electrons are crucial for their physics missions. For future HEP experiments at the energy and intensity frontiers, however, the crystal detectors used in the above mentioned ECALs are either not bright and fast enough, or not radiation hard enough. Crystal detectors have also been proposed to build a Homogeneous Hadron Calorimeter (HHCAL) to achieve unprecedented jet mass resolution by duel readout of both Cherenkov and scintillation light, where development of cost-effective crystal detectors is a crucial issue because of the huge crystal volume required. This paper discusses several R&amp;D directions for the next generation of crystal detectors for future HEP experiments.

This report presents a deduction of a formula which can be used to calculate the light attenuation length of barium fluoride crystals based on the transmittance (or absorbance) data measured by a spectrophotometer.

Because of their high stopping power and fast bright scintillation, cerium doped silicate based heavy crystal scintillators, such as GSO, LSO, and LYSO, have been developed for medical instruments. Their applications in high energy and nuclear physics, however, are limited by lacking high quality crystals in sufficiently large size. The optical and scintillation properties, including the transmittance, emission and excitation spectra and the light output, decay kinetics and light response uniformity, as well as their degradation under gamma-ray irradiation were measured for two long (2.5times2.5times20 cm) LYSO samples from CPI and Saint-Gobain, and were compared to a BGO sample of the same size from SIC. Possible applications for crystal calorimetry in future high energy and nuclear physics experiments are discussed

We report on a study of the correlation between radiation damage of bismuth germanate (BGO) scintillator crystals and trace impurities in the crystal. The light yield and the absorption spectra of doped BGO crystals were measured, both before and after irradiation. While trace concentrations of Cr, Mn, Fe and Pb in BGO were found to lead to substantial radiation damage, traces of Al, Ca, Cu and Si were found to have no measurable effect. Traces of Co, Ga, Mg and Ni were found to have an effect intermediate between the above two groups. Three radiation-induced absorption bands were observed in a set of BGO crystal samples. Their energy levels were found to be independent of the trace elements in the BGO. They are at 2.3±0.1, 3.0±0.1 and 3.8±0.1 eV, respectively, above the valence band. A brief discussion of the radiation damage mechanism in BGO is presented.

With a PETRA energy scan in \ensuremath{\le}30-MeV steps, the continuum production of open top quark up to 38.54 GeV is excluded. Over regions of energy scan from 29.90 to 38.63 GeV limits are set on the product of hadronic branching ratio and electronic width ${B}_{h}{\ensuremath{\Gamma}}_{\mathrm{ee}}$ for toponium to be less than 2.0 keV at the 95% confidence level. By a search for flavor-changing neutral currents in $b$ decay, models without a top quark are excluded.

The measurement of the nonelectromagnetic forward-backward charge asymmetry in the reaction e+eiz'tz at ~s-34.6 GeV and in the angular region 0& IcosOI&0.8 is re- ported.With a systematic error less than 1%, we observe an asymmetry of (-8.1+2.1)/p.This is in agreement with the standard electroweak theory prediction of (-7.6+ 0.6)%.The weak-current coupling constants are also reported.

State-of-the art X-ray imaging cameras using silicon sensors for X-ray detection have demonstrated a frame-rate of 10 MHz and excellent performance for X-ray energies below 20 keV. We proposed a pixelated ultrafast inorganic scintillator-based front imager for GHz hard X-ray imaging. The proposed imager is featured with a total absorption for hard X-ray photons, and provides sub-ns scintillation pulse width crucial for X-ray bunches of a few ns spacing foreseen at the proposed MaRIE facility. We measured temporal response of a dozen ultrafast and fast inorganic scintillators at the 10-ID-B site of the Advanced Photon Source (APS) of ANL. Crystal's response to hybrid X-ray beam of 30 keV, consisting of singlet bunches of 50 ps width and septuplet bunches of 27 ps width with 2.83 ns bunch spacing, was measured. Ultrafast inorganic scintillators, such as BaF2:Y and ZnO:Ga, show clearly resolved X-ray bunches for septuplets, as well as no degradation of amplitude for continuous eight septuplets, providing a proof of principle for the ultrafast inorganic scintillator-based total absorption front imager for the proposed MaRIE project.

Because of its bright and fast scintillation cerium-doped Lu3Al5O12 (LuAG:Ce) crystals have attracted an interest in the high energy physics community. Compared to inorganic crystals, fabrication of ceramic scintillators features with a lower temperature and a more effective use of raw materials, thus promising cost-effective inorganic scintillators. Our investigations revealed excellent radiation hardness of LuAG:Ce ceramics in both transmittance and light output against an ionization dose up to 200 Mrad and a proton fluence up to 3×1014 p/cm2. We also investigated light output and decay kinetics for LuAG:Ce ceramics with different Ce doping levels and various co-dopings. The results show increased light output and slow scintillation component when the Ce doping level increases. Ca2＋ co-doping is found effective in suppressing slow scintillation component in LuAG:Ce ceramics. We also discuss the status of LuAG ceramic scintillators and future development plan.

This report summarizes the quality requirements to the barium fluoride (BaF2) crystals for constructing a high precision electromagnetic calorimeter at future hadron colliders. The basic property of BaF2 crystals and the design and performance of a BaF2 calorimeter are presented. The emphasis of the discussion is in the radiation resistance of the current production BaF2 crystals. An approach to implement optical bleaching in situ is also presented. By using optical bleaching current production quality BaF2 crystals could serve as an excellent candidate to construct a precision calorimeter at future hadron colliders.

The high energy and nuclear physics community is interested in fast bright heavy crystal scintillators, such as cerium-doped LSO and LYSO. An investigation is being carried out to explore the potential use of the LSO and LYSO crystals in future physics experiments. Optical and scintillation properties, including longitudinal transmittance, emission and excitation spectra, light output, decay kinetics and light response uniformity, were measured for three long (2.5×2.5×20 cm) LSO and LYSO samples from different vendors, and were compared to a long BGO sample of the same size. The degradation of optical and scintillation properties under γ-ray irradiations and the radiation-induced phosphorescence were also measured for two long LYSO samples. Possible applications for a crystal calorimeter in future high energy and nuclear physics experiments are discussed.

This paper presents a study of the gamma-ray induced radiation damage effect in large size (2.5 times 2.5 times 20 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) LSO and LYSO crystal samples. Optical and scintillation properties, including longitudinal transmittance and photo-luminescence spectra, light output and light response uniformity with PMT and APD readout, are measured before and after gamma-ray irradiations with an integrated dose up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> rad for three LSO and LYSO samples from different vendors. It was found that 300degC thermal annealing removes all radiation induced absorption. The photo-luminescence spectra measured before and after the irradiations were found to be consistent, indicating that the scintillation mechanism is not damaged. The radiation damage recovers very slow under the room temperature, indicating that the radiation damage level in LSO and LYSO crystals is not dose rate dependent. It was also found that the overall radiation damage in LSO and LYSO crystals is small as compared to other crystal scintillators commonly used in high energy and nuclear physics experiments.

Because of their high stopping power ( 0 = 1 14 cm, Moliere = 2 07 cm) and fast ( 40 ns) bright (4 times of BGO) scintillation, cerium doped lutetium oxyorthosilicate (LSO) and cerium doped lutetium-yttrium oxyorthosilicate (LYSO) crystals have attracted a broad interest in the high energy physics community.This paper presents a comparative study on emission spectra measured for large size BGO, lead tungstate (PbWO 4 ), LSO and LYSO samples excited by UV light (photo-luminescence) with and without internal absorption, x-ray (x-luminescence) and -ray (radio-luminescence).A red shift was observed between the emission spectra with internal absorption as compared to that without.An additional red shift and a significant red component were observed in the radio-luminescence spectra measured for LSO samples but not LYSO samples, which were disappeared after a -ray irradiation with an accumulated dose of 5 10 3 rad.This is the only significant difference observed between the large size LSO and LYSO samples.The origin of these red shifts and the consequence to their light output and applications in the high energy and nuclear physics experiments are discussed.

Gigahertz hard X-ray imaging for the proposed matter-radiation interaction in extreme project presents an unprecedented challenge to front imager in both speed and radiation hardness. Novel fast scintillators are to be developed to face these challenges. This paper presents an investigation on the optical and scintillation properties for a set of fast inorganic scintillators. Transmittance, emission, light output, and decay time were measured. Based on this investigation, we plan to take two approaches to develop inorganic scintillators with subnanoseconds of decay time for the gigahertz hard X-ray imaging. One is yttrium-doped barium fluoride single crystals, and another is based on gallium-doped ZnO nanoparticles.

Future high-energy physics experiments at the energy and intensity frontiers will face a challenge of severe radiation environment from both ionization dose and charged and neutral hadrons. The high-luminosity large hadron collider, for example, will present an environment, where up to 130 Mrad ionization dose, 3 × 1014 charged hadrons/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 5× 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> neutrons/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> are expected. In this paper, we report our investigation on charged hadron-induced radiation damage in BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , LYSO/LFS, and PWO crystals up to 3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> protons/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> by using 800-MeV protons at the Los Alamos Neutron Science Center. Comparison is made between radiation damages induced by protons and ionization dose alone.

Future HEP experiments at the energy and intensity frontiers require fast and ultrafast inorganic scintillators with excellent radiation hardness to face the challenges of unprecedented event rate and severe radiation environment. This paper reports recent progresses in fast and ultrafast inorganic scintillators, such as LYSO:Ce crystals and LuAG:Ce ceramics for an inorganic scintillator based shashlik sampling calorimeter and yttrium doped BaF2 crystals for the proposed Mu2e-II experiment. Applications of ultrafast inorganic scintillators in Gigahertz hard X-ray imaging will also be discussed.

Following a major shortage of 99Mo in the 2009–2010 period, concern grew that the aging reactor production facilities needed to be replaced. Most producers were using highly enriched 235U (HEU) as the target material. The Organisation for Economic Co-...Read More

We report on a study of the radiation resistance and fluorescence of bismuth germanate scintillation crystals doped with europium (BGO: Eu). The transmission spectrum, the light output and the fluorescence spectrum of BGO: Eu crystals were measured before and after irradiation. The radiation resistance of BGO: Eu crystals was found to be increased with increase of europium doping. A red fluorescence emission around 600 nm was found for BGO: Eu samples, which has a 1.5 ms decay time.

This paper reports the results of a study of hadron production in e+e− collisions at c.m. system energies of 33, 35, and 35.8 GeV. Production of a new quark flavor has been sought. The measured values of the total cross section, the thrust distributions, and the study of inclusive muon production show no evidence for the production of a new charge-23e quark near threshold. In addition, during an energy scan in the region 29.9<~√s<~31.6 GeV, no hadron resonance indicating the existence of a bound state composed of charge-23e quarks has been found.Received 1 April 1980DOI:https://doi.org/10.1103/PhysRevLett.44.1722©1980 American Physical Society

The SuperB project is an asymmetric e+e− accelerator of 1036cm−2s−1 design luminosity, capable of collecting a data sample of 50–75ab−1 in five years running. The SuperB electromagnetic calorimeter (EMC) provides energy and direction measurement of photons and electrons, and is used for identification of electrons versus other charged particles. In particular we present its design, geometry study and related simulations, as well as R&D on LYSO crystals and developments on readout electronics. A matrix of 25 crystals has been tested at the Beam Test Facility of Frascati (BTF) in May 2011 at energies between 200 MeV and 500 MeV. Results from this test are presented.

Barium fluoride (BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) crystal has a fast scintillation light peaked at 195 and 220 nm with a sub-ns decay time. This ultrafast scintillation promises a wide application in an area where extreme fast timing is important, such as future high-energy physics experiments, gigahertz hard X-ray imaging, and time-of-flight positron emission tomography. BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> crystal, however, has also a slow scintillation component peaked at 310 nm with a decay time of about 600 ns, which causes pileup. Suppression of the slow scintillation component by selective doping, such as Ce, La, Tm, and Y, was discussed 20 years ago. In this paper, we report suppression of the slow component in BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> crystals by yttrium doping. Single crystals with 1 at% Y doping were grown by vacuum Bridgman technique at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China. Their radioluminescence, optical transmittance, light output, fast/slow ratio, decay kinetics, and light response uniformity were measured. The results show that 1 at% Y doping suppresses the slow scintillation component in BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> crystals by a factor of 6, while the fast component remains unaffected.

Gigahertz (GHz) hard X-ray imaging for the proposed MaRIE project presents an unprecedented challenge for the front imager in both speed and radiation hardness. We proposed two ultrafast inorganic-scintillator-based front imager concepts: a total absorption one and a multilayer one, and investigated optical and scintillation properties for a set of inorganic scintillators at the Caltech HEP crystal laboratory. The results show that yttrium doped barium fluoride crystals and gallium doped ZnO nano-particle-based films are promising for these two concepts, respectively. In this paper, we report their optical and scintillation property as well recent progresses on slow component suppressing in barium fluoride crystals by yttrium doping, and its radiation hardness.

Because of their potential low cost, bright light, and fast decay time, LuAG:Ce ceramic scintillators have attracted a broad interest in the high-energy physics community. One crucial issue for their application in future high-energy physics experiments is their radiation hardness against neutrons and protons expected at future hadron colliders. We report optical and scintillation performance of 1-mm LuAG:Ce ceramic samples doped with Mg^2&#x002B; (and Ca^2&#x002B;) and their radiation damage induced by hadrons. While Mg^2&#x002B; co-doping improves their light output, Ca^2&#x002B; co-doping improves their fast to total (F/T) ratio. LuAG:Ce ceramic samples were irradiated at the Los Alamos Neutron Science Center (LANSCE), Los Alamos, NM, USA, by neutrons up to <inline-formula> <tex-math notation="LaTeX">$6.7\times 10^{15}\,\,\text{n}_{\mathrm {eq}}$ </tex-math></inline-formula>/cm² and by 24-GeV and 800-MeV protons at CERN PS-IRRAD up to <inline-formula> <tex-math notation="LaTeX">$1.2\times 10^{15}$ </tex-math></inline-formula> p/cm² and at LANSCE up to <inline-formula> <tex-math notation="LaTeX">$2.3\times 10^{14}$ </tex-math></inline-formula> p/cm², respectively. All samples show excellent radiation hardness with more than 90&#x0025; of light after irradiation. The RIAC values induced by neutrons are found to be a factor of 2 smaller than lutetium&#x2013;yttrium oxyorthosilicate (LYSO:Ce) crystals. The RIAC values induced by protons are also found a factor of 2 smaller than LYSO:Ce crystals in LuAG:Ce ceramic samples with good optical quality. Research and development will continue to develop LuAG:Ce scintillating ceramics with improved optical quality for future investigation.

The results are reported of a search for excited muons (${\ensuremath{\mu}}^{*}$) and electrons (${e}^{*}$) and for a stable charged heavy lepton by measurements of the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}$, ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}$, ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}\ensuremath{\gamma}$, and $\ensuremath{\gamma}\ensuremath{\gamma}$ final states. Excluded are large regions of the $\ensuremath{\lambda}$ (coupling constant), $M$ (mass) planes for spin-\textonehalf{} ${\ensuremath{\mu}}^{*}$ and ${e}^{*}$, and a new stable charged heavy lepton with mass 14 GeV.

We use the reaction e+ e p, + p, , in the Mark J detector at the DESY high-energy e+ e col- lider PETRA, to test the standard electroweak theory and find good agreement.We also set limits on the parameters of several extended gauge theories.

We report mass limits on the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Z}}^{0}$ and ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}^{\ifmmode\pm\else\textpm\fi{}}$, supersymmetric partners of the ${Z}^{0}$ and ${W}^{\ifmmode\pm\else\textpm\fi{}}$, respectively, using the MARK-J detector at PETRA. The experimental signatures in both cases are acoplanar lepton pairs with missing energy. For the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}^{\ifmmode\pm\else\textpm\fi{}}$, an additional signature is a single energetic lepton. No evidence is found for either the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Z}}^{0}({M}_{{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Z}}^{0}}&lt;35\mathrm{GeV})$ or the ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}^{\ifmmode\pm\else\textpm\fi{}}({M}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{W}}&lt;25\mathrm{GeV})$.

We have used our measurements of final states from e+e− containing an isolated muon and a hadronic or electron shower to search for new spin 0 charged particles. We exclude (95% CL) a supersymmetric partner of the τ with a mass less than 14 GeV/c2. We obtain upper limits on the branching ratio to τvτ for charged Higgs particles or technipions with masses up to 14 GeV/c2. This disagrees with some technicolor model predictions.

We have searched for resonances in the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{hadrons}, \ensuremath{\gamma}\ensuremath{\gamma}, \ensuremath{\mu}\ensuremath{\mu}, \mathrm{and} \mathrm{ee}$, in the energy range $39.79&lt;\sqrt{s}&lt;45.52$ GeV, using the Mark J detector at PETRA. We obtain stringent upper limits on the production of toponium and particles postulated to explain ${Z}^{0}\ensuremath{\rightarrow}\mathrm{lepton}\mathrm{pair}+\ensuremath{\gamma}$ events observed at the CERN $\stackrel{-}{p}p$ collider. We also set limits on the mass and coupling constant of excited electrons.

Because of their high stopping power (X0 = 1.14 cm), fast (t = 40 ns) and bright (4 times of BGO) scintillation and good radiation hardness, cerium doped silicate based heavy crystal scintillators (LSO and LYSO) have attracted a broad interest in the high energy physics community pursuing precision electromagnetic calorimeter in severe radiation environment. We present in this paper current status of large size LSO and LYSO crystals adequate for HEP applications. The optical and scintillation properties and their radiation hardness are discussed.

Studying the accumulation rules of organic matter (OM) in paleo-ocean sediments can not only enhance our understanding of how OM becomes enriched in ancient oceans but also provide guidance for the exploration of shale gas in unconventional shale strata. A breakthrough has been made in shale gas exploration in the early Cambrian Qiongzhusi Formation in South China. However, less attention has been paid to the intraplatform basin of the Yangtze Platform, and the factors controlling organic matter enrichment in this special region remain unclear. This study focuses on a continuous drilling core across the full well section of the Qiongzhusi Formation in the intraplatform basin of the Yangtze Platform. Through the comprehensive analysis of total organic carbon (TOC), major and trace elements, and Mo isotopes, this study investigates the controlling factors for OM enrichment with δ98/95Mo ratios utilized to identify the existence of euxinic bottom water. The examined 240 m long core can be divided into four units, where the TOC values of the lower Units 1 and 2 (0.2–5.0 wt.%) average higher than the upper Units 3 and 4 (0.2–2.5 wt.%). Redox indicators (U/Th, Ni/Co, EF(Mo)—EF(U)) indicate an increasing oxidation of bottom waters from the bottom upwards. δ98/95Mo data further confirm the presence of weakly euxinic conditions in Units 1 and 2, addressing the ongoing controversy surrounding bottom water redox environments. Primary productivity indicators (Ni/Al, Cu/Al) suggest a relatively low average productivity level within the intraplatform basin. The upwelling indicators EF(Co) * EF(Mn) of different profiles in the Yangtze Platform suggest that low productivity within the intraplatform basin can be mainly attributed to the absence of upwelling. Consequently, this study proposes an organic matter enrichment mechanism for the Qiongzhusi Formation in the intraplatform basin, which emphasizes the significance of the redox environment in the formation of high-quality hydrocarbon source rocks in restricted environments that lack upwelling, setting it apart from the deep ocean. These findings have the potential to provide valuable insights for the exploration of high-quality hydrocarbon source rocks in other similar regions.

The RADiCAL Collaboration is conducting R\&D on high performance electromagnetic (EM) calorimetry to address the challenges expected in future collider experiments under conditions of high luminosity and/or high irradiation (FCC-ee, FCC-hh and fixed target and forward physics environments). Under development is a sampling calorimeter approach, known as RADiCAL modules, based on scintillation and wavelength-shifting (WLS) technologies and photosensor, including SiPM and SiPM-like technology. The modules discussed herein consist of alternating layers of very dense (W) absorber and scintillating crystal (LYSO:Ce) plates, assembled to a depth of 25 $X_0$. The scintillation signals produced by the EM showers in the region of EM shower maximum (shower max) are transmitted to SiPM located at the upstream and downstream ends of the modules via quartz capillaries which penetrate the full length of the module. The capillaries contain DSB1 organic plastic WLS filaments positioned within the region of shower max, where the shower energy deposition is greatest, and fused with quartz rod elsewhere. The wavelength shifted light from this spatially-localized shower max region is then propagated to the photosensors. This paper presents the results of an initial measurement of the time resolution of a RADiCAL module over the energy range 25 GeV $\leq$ E $\leq$ 150 GeV using the H2 electron beam at CERN. The data indicate an energy dependence of the time resolution that follows the functional form: $\sigma_{t} = a/\sqrt{E} \oplus b$, where a = 256 $\sqrt{GeV}$~ps and b = 17.5 ps. The time resolution measured at the highest electron beam energy for which data was currently recorded (150 GeV) was found to be $\sigma_{t}$ = 27 ps.

Data-driven methods (DDMs), such as deep neural networks, offer a generic approach to integrated data analysis (IDA), integrated diagnostic-to-control (IDC) workflows through data fusion (DF), which includes multi-instrument data fusion (MIDF), multi-experiment data fusion (MXDF), and simulation-experiment data fusion (SXDF). These features make DDMs attractive to nuclear fusion energy and power plant applications, leveraging accelerated workflows through machine learning and artificial intelligence. Here we describe Physics-informed Meta-instrument for eXperiments (PiMiX) that integrates X-ray (including high-energy photons such as $\gamma$-rays from nuclear fusion), neutron and others (such as proton radiography) measurements for nuclear fusion. PiMiX solves multi-domain high-dimensional optimization problems and integrates multi-modal measurements with multiphysics modeling through neural networks. Super-resolution for neutron detection and energy resolved X-ray detection have been demonstrated. Multi-modal measurements through MIDF can extract more information than individual or uni-modal measurements alone. Further optimization schemes through DF are possible towards empirical fusion scaling laws discovery and new fusion reactor designs.

<title>Abstract</title> Helical milling is widely used in aerospace as a key processing technology for Carbon fiber reinforced polymer (CFRP). However, the eccentric machining characteristics lead to an unusually complex pattern of cutting force and residual stress distribution on the work-piece during helical milling processing. Based on the Hashin failure criterion, a 3D FEM model of CFRP helical milling was built for analyzing the changing law of cutting force, then the three factors and three levels orthogonal tests were used to investigate the influence of machining parameters on axial force, radial force and minimum principal residual stress, finally the multi-objective optimization based on grey correlation analysis was realized. Results showed that the errors of axial force and radial force obtained by simulation and experiment were 10.68% and 12.26%, respectively. The axial force and radial force were negatively correlated to the spindle speed, positively correlated to the axial cutting depth, and uncorrelated to the feed per tooth. The minimum principal residual stress was negatively correlated to the spindle speed, positively correlated to the feed per tooth, and uncorrelated to the axial cutting depth. The degree of influence on optimization of machining parameters was: spindle speed&gt;axial cutting depth&gt;feed per tooth. The corresponding average grey correlation degree differences were 0.280981, 0.216859 and 0.013422, respectively. The maximum value of grey correlation degree in the orthogonal test was 0.874372, and the corresponding optimal parameters combination was the spindle speed 8000 r/min, feed per tooth 0.03 mm/z and axial cutting depth 0.2 mm/r.

Light monitoring will play a crucial role in maintaining energy resolution for the CMS lead tungstate crystal calorimeter at LHC. In the last several years, a laser based monitoring light source was designed and constructed at Caltech, and was installed and commissioned at CERN. This paper presents the design of the CMS ECAL monitoring light source and its performance during beam tests. Issues related to the monitoring precision are discussed.

We use the reaction e+e−→hadrons, in the Mark J detector at the DESY electron-positron collider PETRA, to determine the hadronic cross section up to 46.78 GeV. The production of a top quark with a charge equal to (2/3) is excluded up to 46.6 GeV with 95% C.L. The observed rise in the cross section at higher energies is consistent with the electroweak prediction for a Z0 mass of 93 GeV. We describe some unusual muon inclusive events.Received 27 January 1986DOI:https://doi.org/10.1103/PhysRevD.34.681©1986 American Physical Society

We report on the results of the study of e+e− collisions at the highest PETRA energy of √s = 31.57 GeV, using the 4π sr, electromagnetic and calorimetric detector Mark J. Based on 88 hadron events, and an integrated luminosity of 243 nb−1 we obtain R = σ(e+e− → hadrons)/σ(e+e− → μ+μ−) = 4.0 ± 0.5 (statistical) ± 6 (systematic). The R value, the measured thrust distribution and average spherocity show no evidence for the production of new quark flavors.

An effort was made to introduce scintillation light in lead fluoride crystals by selective doping. It was found that some rare earth ions doped in the lead fluoride crystal may serve as luminescence centers. The photo- and X- luminescence spectra, the decay time constants and the light outputs were measured for these doped samples. The decay time was found to be at a few milliseconds for these rare earth doped lead fluoride samples, which is too long to be useful for the homogeneous hadronic calorimeter detector concept with dual readout for future high energy physics experiments. Work to introduce scintillation in lead fluoride will continue.

Crystal calorimeter has traditionally played an important role in precision measurement of electrons and photons in high energy physics experiments. Recent interest in calorimeter technology extends its application to measurement of hadrons and jets with dual readout for both Cherenkov and scintillation light. Optical and scintillation properties of crystal scintillators commonly used in particle physics experiments are reviewed. Technologies to discriminate Cherenkov and scintillation light is elaborated. Candidate crystals for the homogeneous hadronic calorimeter detector concept and their recent development are discussed.

Because of their ultrafast scintillation with subnanosecond decay time, barium fluoride (BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) crystals have attracted broad interest in the high energy physics and nuclear physics communities. One crucial issue, however, is its slow scintillation component with 600-ns decay time, which causes pile-up in a high rate environment. Previous studies show that the slow component can be suppressed effectively by rare earth doping. In this paper, we report investigations on a set of Φ 18 × 21 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> cylinders doped with different yttrium levels grown at Beijing Glass Research Institute (BGRI), from which the optimized yttrium doping level was determined. A Φ 40 × 160 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ingot with 5 atomic % (at.%) yttrium doping was consequently grown at BGRI and was used to cut one 25 × 25 × 100 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> crystal and several thin slices. Their optical and scintillation properties were measured at Caltech. The results show that yttrium doping effectively suppresses the slow component while maintaining its ultrafast light unchanged. Research and development will continue to develop large-size BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> :Y crystals with improved optical quality for a fast BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> :Y crystal calorimeter for Mu2e-II.

One crucial issue for the application of scintillation crystals in future high-energy physics experiments is radiation damage in a severe radiation environment, such as the high luminosity large hadron collider. While radiation damage induced by ionization dose in inorganic scintillators is well understood, investigations are ongoing to understand radiation damage induced by hadrons, including both charged hadrons and neutrons. Aiming at understanding neutron-induced radiation damage in fast inorganic scintillators, lutetium yttrium oxyorthosilicate (LYSO)/lutetium fine silicate (LFS), BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and PWO crystals were irradiated at Los Alamos Neutron Science Center by a combination of particles, including neutrons, protons, and γ-rays. The results indicate that LYSO/LFS and BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> crystal plates are radiation hard up to a 1-MeV equivalent neutrons fluence of 9 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> equivalent neutron (neq)/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , but not PWO, and the neutron-induced radiation damage in LYSO crystals is a factor of ten less than protons.

This report presents the result of a study on radiation-induced color center densities in La-doped lead tungstate (PbWO4) crystals. The creation and annihilation constants of radiation-induced color centers were determined by using transmittance data measured for a PbWO4 sample before and during 60Co γ-ray irradiation at a dose rate of 15 rad/h. Following a model of color center kinetics, these constants were used to calculate color center densities under irradiations at 100 rad/h. The result was found to be in good agreement with experimental data, indicating that the behaviour of PbWO4 crystals under irradiation can be predicted according to this model.

This report presents recent progress of a study on the radiation damage in lead tungstate (PbWO/sub 4/) crystals. The dose rate dependence of radiation damage in PbWO/sub 4/ has been observed. An optimization of the oxygen compensation through post-growth thermal annealing has led to PbWO/sub 4/ samples with significantly improved radiation hardness. Front irradiation is found to cause a factor of 2 to 6 times less severe damage than uniform irradiation. Lanthanum doping was found not to be a determining factor for PbWO/sub 4/ radiation hardness improvement. Finally, a TEM/EDS analysis revealed that the radiation damage in PbWO/sub 4/ crystals is caused by oxygen vacancies.

Precision crystal calorimetry in future high energy physics experiments faces a new challenge to maintain its precision in a hostile radiation environment. This paper reviews the radiation hardness requirements to the crystal scintillators and approaches to develop high quality scintillating crystals. Two on-going efforts are discussed in detail: the CsI(Tl) crystal development for the BaBar experiment at SLAC and the progress of the PbWO/sub 4/ crystal quality for the CMS experiment at LHC.

Because of their high stopping power and fast and bright scintillation, cerium doped LSO and LYSO crystals have attracted a broad interest in the physics community pursuing precision electromagnetic calorimeter for future high energy physics experiments. Their excellent radiation hardness against γ -rays, neutrons and charged hadrons also makes them a preferred material for calorimeters to be operated in a severe radiation environment, such as the HL-LHC. An effort was made at SIPAT to grow 25 X <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (28 cm) long LYSO crystals for high energy physics applications. In this paper, the optical and scintillation properties and its radiation hardness against γ -ray irradiations up to 1 Mrad are presented for the first 2.5×2.5×28 cm LYSO sample. An absorption band was found at the seed end of this sample and three other long samples, which was traced back to a bad seed crystal used in the corresponding crystal growth process. Significant progresses in optical and scintillation properties were achieved for large size LYSO crystals after eliminating this absorption band.

Crystal detectors have been used widely for decades in high energy and nuclear physics experiments, medical instruments and homeland security applications. Novel crystal detectors are continuously being found. Future HEP experiments require bright and fast crystal detectors with excellent radiation hardness. Cost-effectiveness is also a crucial issue for crystal detectors to be used in a large volume. To face these new challenges a thorough R&D program is required to investigate and develop crystal detectors for future HEP experiments in all frontiers.

This report presents results on optical bleaching for 25 cm long BaF2 crystals to be used in constructing a BaF2 calorimeter at the SSC. A practical scenario of implementing optical bleaching in situ and the requirements on the light sources used to bleach the entire GEM BaF2 calorimeter are presented.

This paper presents result of a study on undoped as well as various doped lead tungstate crystals. Radiation induced color center density was compared to radioluminescence. Light output degradation for crystals under irradiation was measured. Correlations between variations of crystal transmittance and light output were investigated. Monitoring wavelength was determined so that adequate sensitivity and good linearity may be achieved.

In this paper we present results of a study on the yttrium doping in lead tungstate crystals. The crystal growth by modified Bridgman method is described. Results of trace analysis on raw materials and crystals are presented. The segregation coefficient of yttrium ions in lead tungstate crystals was determined. The scintillation emission and longitudinal transmittance spectra, light output, decay kinetics, light response uniformity and radiation damage were measured. It is found that yttrium doping suppresses slow scintillation component and improves radiation hardness of lead tungstate crystals.

Because of the broad interest in high energy and nuclear physics community, mass production capacities of lead tungstate crystals have been established. The optical and scintillation properties of lead tungstate crystals, 20 each from two major vendors, were evaluated. The transmittance, emission and excitation spectra, light output and light response uniformity of these samples were measured. The degradations of these properties under irradiation, and the emission weighted radiation induced absorption coefficient (EWRIAC) were also studied. It was found that currently mass-produced lead tungstate crystals are radiation hard enough for radiation environments where expected dose rates do not exceed a few hundred rad/h.

Crystal calorimeter has traditionally played an important role in precision measurement of electrons and photons in high energy physics experiments. Recent interest in calorimeter technology extends its application to measurement of hadrons and jets with dual readout. Potential application of new generation scintillating crystals of high density and high light yield, such as cerium doped LSO and LYSO, in high energy physics experiments is described. Candidate crystals for the homogeneous hadronic calorimeter concept are also discussed.

Neutron induced nuclear counter effect in Hamamatsu silicon PIN diodes and APDs was measured by irradiating fast neutrons from a pair of 252 Cf sources directly to these devices. It was found that the entire kinetic energy of these neutrons may be converted into electron signals in these devices, leading to anomalous signals of up to a few million electrons in a single isolated calorimeter readout channel. Signals of such amplitude represent equivalent energy of several hundred GeV and a few GeV for PWO and LSO/LYSO crystals respectively assuming the corresponding light yields of 4 and 800 p.e./MeV. The overall rate of the neutron induced nuclear counter effect in APDs is found to be more than an order of magnitude less than that in PIN diodes. Increasing the APD gain was also found to reduce the neutron induced nuclear counter effect. An intelligent front-end chip capable of selecting un-contaminated signal is proposed to eliminate completely the nuclear counter effect without significant cost increase.

This paper reports proton-induced radiation damage in fast crystal scintillators. Large size LYSO and CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> crystals of 20 and 15 cm long were irradiated by 800 MeV protons at Los Alamos up to 3.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> p/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with degradation and recovery of their longitudinal transmittance measured in situ. LYSO plates of 14× 14×1.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> were irradiated by 67 MeV protons at UC Davis up to 9.5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> p/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and by 24 GeV protons at CERN up to 6.9×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> p/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The results show an excellent radiation hardness of LYSO crystals against charged hadrons.

The Mu2e experiment is constructing a calorimeter consisting of 1348 undoped cesium iodide (CsI) crystals in two disks. Each crystal has a dimension of 34 × 34 × 200 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and is readout by a large-area silicon photomultipliers array. A series of technical specifications on mechanical and optical parameters was defined according to the calorimeter physics requirements. Preproduction CsI crystals were procured from three firms: Amcrys, Saint-Gobain, and Shanghai Institute of Ceramics. We report the quality assurance on crystal's scintillation properties and their radiation hardness against ionization dose and neutrons. With a fast decay time of about 30 ns and a light output of more than 100 p.e./MeV measured by a bialkali photomultiplier tube, undoped CsI crystals provide a cost-effective solution for Mu2e.

This paper reports proton induced radiation damage in fast crystal scintillators. A 20 cm long LYSO crystal, a 15 cm long CeF3 crystal and four liquid scintillator based sealed quartz capillaries were irradiated by 800 MeV protons at Los Alamos up to 3.3×1014p/cm2. Four 1.5 mm thick LYSO plates were irradiated by 24 GeV protons at CERN up to 6.9×1015p/cm2. The results show an excellent radiation hardness of LYSO crystals against charged hadrons.

Diamond, a highly radiation-resistant material, is considered a nearly ideal material for radiation detection, particularly in high-energy physics. In this study, radiation damage from high-energy proton beams was induced in diamond crystals to determine exposure lifetime in detectors made from this material; the effects were investigated using non-destructive x-ray techniques and through the FLUKA simulation package. Two diamond detectors were irradiated by an 800 MeV proton beam at different fluence rates, and the real-time current response was recorded to observe degradation in the signal over time. It was determined that the proton fluence rate had a significant effect on the device degradation. The detector performance from the irradiated detectors was characterized using x-ray beam-induced current measurements, and the mechanism of proton radiation damage to diamond sensors, especially the radiation effects on carrier transport, was studied. The vacancies generated from proton irradiation were considered the major source of detector degradation by trapping holes and inducing an internal electric field. Simulation results from the FLUKA package revealed an uneven distribution of the radiation-induced vacancies along the beam path, and the corresponding detector signals calculated from the simulation results displayed a good match to the experimental results.

This report summarizes main results of a study on scintillation properties and radiation resistance of large size undoped cesium iodide (CsI) crystals produced in former Soviet Union. The results of this study indicate that with existing quality, undoped CsI crystal may be used in high counting rate environment with integrated radiation dosage up to 10 krads. Improvements in radiation resistance are needed, however, if they are to be used in very high radiation environment, such as SSC and LHC.

We report on the determination of trace elements in a set of Bi4Ge3O12 (BGO) crystals by neutron activation analysis. By using doped polycrystalline BGO powders as calibration standards, we have measured the concentrations of Al, Mn, Cu, Co, Cr and Fe in the crystals with a sensitivity of 0.5–500 ppb, and we have determined the segregation coefficients. We have also studied the correlation between the trace elements and the “radiation damage” (color center formation) effect.

A QuEChERS-LC-Q-TOF/MS analysis method for the detection of 255 pesticides in Radix Codonopsis and Angelica sinensis decoctions was established. The transfer behaviours of 22 frequently detected pesticides were analysed.

Introduction In the context of declining mortality rates and increasing infectivity, it has become unavoidable for the majority of individuals to experience a COVID-19 infection at some point. This study aimed to investigate the psychological well-being of the general population during China’s transition period from strict control measures to relaxed policies in COVID-19 prevention and control, as well as the impact of COVID-19 related thoughts on emotion and life satisfaction during widespread infections. Methods A cross-sectional study was conducted involving a sample size of 1578 participants. Participants completed self-report questionnaires assessing positive and negative emotions, thoughts about COVID-19, and satisfaction with life. Demographic characteristics such as sex, age, and education level were controlled for in the analysis. Results The findings revealed that individuals who had been infected with COVID-19 (specifically the Omicron variant BA.5.2 or BF.7) reported lower levels of positive emotions compared to those who were uninfected or had recovered from the infection. There was a significant relationship between COVID-19-related thoughts, emotions, and life satisfaction. Positive COVID-19 related thoughts were found to mediate the relationship between negative emotions and satisfaction with life. Discussion This study represents a comprehensive examination conducted in China, focusing on assessing the impact of the COVID-19 pandemic on the general population during the critical transition period from control to relaxation. Throughout this period, the number of infections experienced fluctuations, initially rising but eventually declining over a one-month span. In such a momentous historical period, maintaining a positive perspective on COVID-19 and its management becomes paramount in enhancing the emotional well-being, life satisfaction and overall well-being of individuals.

This work presents an analytical method for rapidly screening multiple pesticide residues using QuEChERS combined with ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry.

Abstract We report on a study of the light yield and surface treatment of barium fluoride (BaF 2 ) scintillation crystals. Using a bialkali photocathode the photoelectron (p.e.) yield of BaF 2 crystals was measured to be 130 p.e./MeV for the fast components and 700 p.e./MeV for the slow component. A somewhat hygroscopic nature for the BaF 2 is found. Teflon film was found to be the best wrapping material for the BaF 2 crystals. The radiation damage of the BaF 2 crystals can be fully annealed under 500 ° C for 3 hours.

The Mark J Collaboration at the DESY e+e− collider PETRA presents results on the electroweak reactions e+e−→μ+μ−τ+τ−,μ+μ−γ, and e+e−μ+μ−. The c.m. energy range is 12 to 46.78 GeV. In the μ+μ− and τ+τ− channels the total cross sections and the forward-backward asymmetries are reported and compared with other experiments. The results are in excellent agreement with the standard model. The weak-neutral-current vector and axial-vector coupling constants are determined. The values for muons and τ’s are compatible with universality and with the predictions of the standard model. In the μ+μ−γ channel, all measured distributions, including the forward-backward muon asymmetry, are in excellent agreement with the electroweak theory. Our data on the two-photon process, e+e−μ+μ−, agrees with QED to order α4 over the entire energy range and the Q2 range from 0.7 to 166 GeV2.Received 29 April 1988DOI:https://doi.org/10.1103/PhysRevD.38.2665©1988 American Physical Society

A study of τ-lepton production in the CMS energy region from 14 to 46.8 GeV at PETRA is reported. The cross section, the decay branching ratio into μνν, and the electroweak parameters are determined with a total integrated luminosity of 115 pb−1.

We have performed a high statistics measurement of the production rate and the energy flow pattern of hadron events between √s=33 and 36.7 GeV. The data show no evidence for the production of a new quark with charge 23e. Planar events in e+e−→hadrons are shown to have three well separated jets. The production rate and the shape of three-jet events are compared with many models and we find that only the QCD model can explain the data.

This paper compares ¿-ray induced radiation damage effect in two kinds of heavy crystal scintillators: PWO and LSO/LYSO. Scintillation emission, optical transmission, light output, decay kinetics and light response uniformity were measured for PWO and LSO/LYSO crystal samples of large size before and after ¿-ray irradiations. ¿-ray induced phosphorescence was also measured, and the corresponding readout noise was determined.

A multilayer thin-scintillator concept is described for ultrafast imaging. The individual layer thickness is determined by the spatial resolution and light attenuation length, the number of layers is determined by the overall efficiency. By coating the scintillators with a high quantum-efficiency photocathode, single X-ray photon detection can be achieved using fast scintillators with low light yield. The fast, efficient sensors, when combined with MCP and novel nanostructed electron amplification schemes, is a possible way towards GHz hard X-ray cameras for a few frames of images.

A very compact crystal based shashlik calorimeter is proposed for future HEP experiments in an extreme harsh radiation environment, such as the proposed HL-LHC. Thin crystal plates are used as the sensitive medium to reduce the light path length and thus the radiation damage effects and the calorimeter cost. A design of such a calorimeter uses tungsten as absorber, LYSO crystals as active medium, and liquid scintillator filled quartz capillaries as WLS to transport scintillating light to photodetectors. Initial calorimeter design and performance of prototype modules are presented. Possible optimizations are discussed.

Light monitoring will serve as an intercalibration for Compact Muon Solenoid (CMS) lead tungstate crystals in situ at the Large Hadronic Collider, which is crucial for maintaining crystal calorimeter's subpercent constant term in the energy resolution. This paper presents the design of the CMS electromagnetic calorimeter monitoring light source and high-level distribution system. The correlations between variations of the light output and the transmittance for the CMS choice of yttrium-doped PbWO/sub 4/ crystals were investigated and were used to study monitoring linearity and sensitivity as a function of wavelength. The monitoring wavelength was determined so that a good linearity as well as adequate sensitivity can be achieved. The performance of a custom manufactured tunable laser system is presented. Issues related to monitoring precision are discussed.

A new calibration technique based on radiative capture of protons from an RFQ accelerator in a lithium target, which makes use of the resultant high intensity flux of 17.6 MeV photons, has been developed and tested. The technique is capable of calibrating the thousands of BGO crystals in the L3 electromagnetic calorimeter at once, with an absolute accuracy of better than 1% in 1–2 h. Systematic errors in the calibration, which have been studied earlier through Monte Carlo simulations, have been experimentally proven to be small and calculable, and are expected to be much less than 1%. When installed in the L3 experiment at LEP, this system will help ensure that the high resolution of the L3 electromagnetic calorimeter is maintained during running.

A direct test is presented of higher-order QED (${\ensuremath{\alpha}}^{4}$) at large momentum transfers (up to \ensuremath{\sim}100 Ge${\mathrm{V}}^{2}$). These tests were carried out with the MARK-J detector at PETRA by comparing the measured cross section for the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ with the prediction of QED for $12 \mathrm{GeV}&lt;~\sqrt{s}&lt;~36.7 \mathrm{GeV}$. The cross sections and the various kinematic distributions agree with QED.

A precision lead tungstate crystal calorimeter is being constructed by the CMS collaboration as a powerful tool to probe electroweak symmetry breaking and new physics in the LHC era. The status of calorimeter construction is reported. A crucial issue of maintaining crystal calorimetry precision in the expected radiation environment is elaborated.

Crystal calorimeter has traditionally played an important role in precision measurement of electrons and photons in high energy physics experiments. Recent interest in calorimeter technology extends its application to measurement of hadrons and jets with dual readout for both Cherenkov and scintillation light. Optical and scintillation properties of crystal scintillators commonly used in particle physics experiments are reviewed. Technologies to discriminate Cherenkov and scintillation light is elaborated. Candidate crystals for the homogeneous hadronic calorimeter detector concept and their recent development are discussed.

Gigahertz (GHz) imaging technology will be needed at high-luminosity X-ray and charged particle sources. It is plausible to combine fast scintillators with the latest picosecond detectors and GHz electronics for multi-frame hard Xray imaging and achieve an inter-frame time of less than 10 ns. The time responses and light yield of LYSO, LaBr₃, BaF₂ and ZnO are measured using an MCP-PMT detector. Zinc Oxide (ZnO) is an attractive material for fast hard X-ray imaging based on GEANT4 simulations and previous studies, but the measured light yield from the samples is much lower than expected.

We report status of alkali-free cerium-doped and co-doped fluorophosphate glasses as a potential inorganic scintillator for future high energy physics experiments. Optical and scintillation properties, such as emission, transmittance, light output, decay time and their degradation after γ-ray irradiations, are measured for glass samples produced at AFO Research Inc. Further developments are needed for this potential cost-effective glass scintillator to be used for the HHCAL detector concept.

Because of its high density and superior quality factor, sapphire crystal, as a candidate material for test masses, has attracted much attention in gravitation wave communities. The use of sapphire crystal, however, is limited by its size, homogeneity, and absorption. An effort has been made to overcome these difficulties at the Shanghai Institute of Optics and Fine Mechanics in collaboration with the Laser Interferometer Gravitational-Wave Observatory Laboratory. By using a directional temperature gradient technique (TGT), sapphire crystals of 11 cm in diameter and 8 cm in length were grown at the C plane (0001). The results indicate that a homogeneity of <5/spl times/10/sup -7/ and an absorption of 35-65 ppm/cm have been achieved at wavelength of 1.06 /spl mu/m. This paper presents the TGT growth of sapphire crystals, their transmittance spectra, optical homogeneity, and absorption. Future applications for gravitational wave experiments are discussed.

In this paper, we report an investigation on the radiation damage effects induced by neutrons in large size crystal scintillator: BGO, CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , LYSO:Ce and PWO. The irradiations were carried out by using fast neutrons from one <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">241</sup> Am-Be and two <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">252</sup> Cf sources. The optical and scintillation properties of these samples, including UV excitation and emission spectra, longitudinal transmission, light output, decay kinetics and light response uniformity, were measured before and after the irradiations. The neutron induced photo-current was also measured, and was used to estimate the readout noise under the neutron flux expected by an electromagnetic calorimeter at a very severe radiation environment. Because of its high light output and excellent radiation resistance LYSO:Ce crystal is found to have the smallest neutron induced readout noise as compared to other large size crystals, indicating it is a good candidate material for a future crystal calorimeter in a severe radiation environment.

Future HEP experiments at the energy and intensity frontiers require fast inorganic crystal scintillators with excellent radiation hardness to face the challenges of unprecedented event rate and severe radiation environment. This paper reports recent progress in application of fast inorganic scintillators in future HEP experiments, such as thin layer of LYSO crystals for a shashlik sampling calorimeter and a precision TOF detector proposed for the CMS upgrade at HL-LHC, undoped CsI crystals for the Mu2e experiment at Fermilab and yttrium doped BaF2 crystals for Mu2e-II. Applications of very fast crystal scintillators for Gigahertz hard X-ray imaging for the proposed Marie project at LANL will also be discussed.

Particle colliders operating at high luminosities present challenging environments for high energy physics event reconstruction and analysis. We discuss how timing information, with a precision on the order of 10 ps, can aid in the reconstruction of physics events under such conditions. We present calorimeter based timing measurements from test beam experiments in which we explore the ultimate timing precision achievable for high energy photons or electrons of 10 GeV and above. Using a prototype calorimeter consisting of a 1.7×1.7×1.7 cm3 lutetium–yttrium oxyortho-silicate (LYSO) crystal cube, read out by micro-channel plate photomultipliers, we demonstrate a time resolution of 33.5±2.1 ps for an incoming beam energy of 32 GeV. In a second measurement, using a 2.5×2.5×20 cm3 LYSO crystal placed perpendicularly to the electron beam, we achieve a time resolution of 59±11 ps using a beam energy of 4 GeV. We also present timing measurements made using a shashlik-style calorimeter cell made of LYSO and tungsten plates, and demonstrate that the apparatus achieves a time resolution of 54±5 ps for an incoming beam energy of 32 GeV.

We report on three LYSO crystal batches characterized at the Caltech crystal laboratory for future HEP experiments: 25 20 cm long crystals for the SuperB experiment; 12 13 cm long crystals for the Mu2e experiment and 623 14×14×1.5 mm3 plates with five holes for a LYSO/W Shashlik matrix for a beam test at Fermilab. Optical and scintillation properties measured are longitudinal transmittance, light output and FWHM energy resolution. Correlations between these properties are also investigated.

The Mu2e experiment at Fermilab will search for the charged-lepton flavor violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. The calorimeter plays an important role in providing a fast trigger filter, excellent particle identification and a seeding for track reconstruction. Its requirements are to provide an energy (timing) resolution better than 10% (0.5 ns) and a position resolution below 1 cm, for 100 MeV electrons. The calorimeter consists of two disks, each one made of 674 un-doped CsI crystals readout by two large area arrays of 2 × 3 UV-extended SiPMs of 6×6 mm2 dimensions. A large scale prototype (Module-0) has been constructed and tested with an electron beam in the energy range between 60 and 120 MeV at the BTF of Frascati National Laboratories. Results demonstrated that this calorimeter satisfies the Mu2e requirements.

One crucial issue for applications of inorganic scintillators in future HEP experiments is radiation damage in a severe radiation environment, such as the HL-LHC. While radiation damage induced by ionization dose is well understood, investigations are on-going to understand radiation damage induced by hadrons, including both charged hadrons and neutrons. Aiming at understanding neutron induced radiation damage in fast inorganic scintillators, BaF2, LYSO/LFS and PWO crystals were irradiated at LANSCE by a combination of particles, including neutrons, protons and γ-rays. The results indicate that LYSO/LFS and BaF2 crystal plates are radiation hard up to 4 × 1015 fast neutrons/cm2.

Recent advances in ghost imaging techniques and X-ray sources such as synchrotrons and, more recently, X-ray free-electron lasers (XFEL) have made X-ray ghost imaging a growing topic of interest. One specific type of ghost imaging utilizes thermal radiation and the measurement of intensity fluctuation correlation to form a true image without the need of a lens. This technique allows for much higher resolution than traditional X-ray imaging for a mesoscopic or even a microscopic object. In addition to this benefit of not requiring a lens, a surprising experiment has shown that, when set up correctly, this type of ghost imaging can provide clear images through the measurement of intensity fluctuation correlation when traditional images through measurements of intensity are blurred due to optical turbulence and vibrations. This turbulence-free technique will help maintain the high resolution of X-ray ghost imaging. How is an image formed from fluctuations in light? And what makes it turbulence-free? Using the concept of two-photon interference, this article provides an introduction to these fundamentally interesting concepts and X-ray ghost imaging.

Because of its fast scintillation peaked at 220 nm with a decay time of less than 0.6 ns, barium fluoride crystals have attracted broad interest in the community pursuing ultrafast detectors for future high energy physics (HEP) experiments and GHz hard X-ray imaging for future X-ray free-electron laser (XFEL) facilities. A crucial issue for its application is the spectral response of photodetectors down to vacuum ultraviolet (VUV). In this article, we compare quantum efficiency (QE) and photon detection efficiency (PDE) spectra measured for several ultraviolet (UV) photodetectors down to 200 nm. Their figures of merit on the detection efficiency for the fast component and the suppression of the slow component are also discussed.

To address the challenges of providing high-performance calorimetry in future hadron collider experiments under conditions of high luminosity and high radiation (FCC-hh environments), we conducted R&amp;D on advanced calorimetry techniques suitable for such operation, based on scintillation and wavelength-shifting technologies and photosensor (SiPM and SiPM-like) technology. In particular, we focused our attention on ultra-compact radiation-hard EM calorimeters based on modular structures (RADiCAL modules) consisting of alternating layers of the very dense absorber and scintillating plates, read out via radiation hard wavelength shifting (WLS) solid fiber or capillary elements to photosensors positioned either proximately or remotely, depending upon their radiation tolerance. RADiCAL modules provide the capability to measure simultaneously and with high precision the position, energy and timing of EM showers. This paper provides an overview of the instrumentation and photosensor R&amp;D associated with the RADiCAL program.

Fast and heavy inorganic scintillators with suitable radiation tolerance are required to face the challenges presented at future hadron colliders of high energy and intensity. Up to 5 GGy and 5 × 1018 neq/cm2 of one-MeV-equivalent neutron fluence is expected by the forward calorimeter at the Future Hadron Circular Collider. This paper reports the results of an investigation of proton- and neutron-induced radiation damage in various fast and heavy inorganic scintillators, such as LYSO:Ce crystals, LuAG:Ce ceramics, and BaF2 crystals. The experiments were carried out at the Blue Room with 800 MeV proton fluence up to 3.0 × 1015 p/cm2 and at the East Port with one MeV equivalent neutron fluence up to 9.2 × 1015 neq/cm2, respectively, at the Los Alamos Neutron Science Center. Experiments were also carried out at the CERN PS-IRRAD proton facility with 24 GeV proton fluence up to 8.2 × 1015 p/cm2. Research and development will continue to develop LuAG:Ce ceramics and BaF2:Y crystals with improved optical quality, F/T ratio, and radiation hardness.

The Mu2e experiment at Fermilab will search for Charged Lepton Flavor Violating conversion of a muon to an electron in an atomic field. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external system, surrounding the solenoid, to veto cosmic rays. The calorimeter plays an important role to provide: a) excellent particle identification capabilities; b) a fast trigger filter; c) an easier tracker track reconstruction. Two disks, located downstream of the tracker, contain 674 pure CsI crystals each. Each crystal is read out by two arrays of UV-extended SiPMs. The choice of the crystals and SiPMs has been finalized after a thorough test campaign. A first small scale prototype consisting of 51 crystals and 102 SiPM arrays has been exposed to an electron beam at the BTF (Beam Test Facility) in Frascati. Although the readout electronics were not the final, results show that the current design is able to meet the timing and energy resolution required by the Mu2e experiment.

In high-energy and nuclear physics experiments, total absorption electromagnetic calorimeters made of inorganic crystals are known for their superb energy resolution and detection efficiency for photon and electron measurements. A crystal calorimeter is thus the choice for those experiments where precision measurements of photons and electrons are crucial for their physics missions. It is also known that the existing crystal detectors are neither bright nor fast enough nor radiation hard enough to survive severe radiation environment expected in future HEP experiments. Crystal detectors have also been proposed to build a homogeneous hadron calorimeter to achieve unprecedented jet mass resolution by duel readout of both Cherenkov and scintillation light, where the development of cost-effective crystal detectors is a crucial issue because of the 100 cubic meters crystal volume required. To develop novel inorganic crystal scintillator-based detector concepts for future HEP experiments at the energy and intensity frontiers. Optical and scintillation properties of novel inorganic crystal scintillators, such as excitation, emission and transmittance spectra, light output and decay time, are characterized before and after irradiation by ionization dose and hadrons. Their performance and radiation hardness are compared to the requirements, and feedback is given to the crystal manufacturers for quality improvement. As a result of this investigation, several inorganic crystal scintillator-based detector concepts are established for future HEP experiments, such as an LSO/LYSO crystal-based total absorption and/or sampling calorimeter concept, a barium fluoride crystal-based very fast crystal calorimeter concept, and a cost-effective inorganic scintillator-based homogeneous hadron calorimeter concept. Bright, fast and radiation hard LYSO/LSO crystals may be used for a total absorption ECAL. An LYSO/W Shashlik sampling calorimeter will survive the harsh radiation environment expected at the HL-LHC. With sub-ns decay time of its fast scintillation component and excellent radiation hardness, barium fluoride crystals would provide more than ten times faster rate and timing capability, provided that their slow scintillation component is effectively suppressed to avoid pileup. PbF2, PbFCl and BSO crystals may provide a foundation for a homogeneous hadron calorimeter with dual readout for both Cherenkov and scintillation light to achieve unprecedented jet mass resolution for future lepton colliders.

Gigahertz hard X-ray imaging presents an unprecedented challenge to both timing and spatial resolutions for inorganic scintillator-based front imagers. A beam test with 30-keV X-rays from the Advanced Photon Source (APS) showed that 5-mm BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plates resolve well 30-keV X-ray septuplets of 27-ps width and 2.83-ns spacing. Pixelated crystal screens with a pitch down to 400 μm were fabricated by mechanic slicing for BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , BaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> :Y, and LYSO crystals. Their spatial resolution and detection efficiency for hard X-rays are defined by the pitch and thickness, respectively. Thicker monolithic crystal screens show poorer spatial resolution, which may be improved using a small optical aperture with a loss in both efficiency and dynamic range for hard X-rays. Future plans include pursuing smaller crystal pitches by laser slicing and research and development on novel ultrafast inorganic scintillators.

We report an investigation on optical and scintillation properties and radiation hardness of four 20 cm long BSO crystals grown at SIC for the HHCAL detector concept. Their optical and scintillation properties, such as longitudinal transmittance, light output and light response uniformity, were measured before and after γ-ray irradiation. Progresses are observed in optical quality, light output and radiation hardness. Their use for HHCAL concept is discussed.

Because of their high stopping power and fast scintillation, lead tungstate crystals have attracted much attention in the high energy physics and nuclear physics communities. The use of lead tungstate, however, is limited by its low light output. An effort has been made at the Shanghai Institute of Ceramics to improve this. The results indicate that a factor of ten increase of the light output, mainly in the microsecond decay component, may be achieved. The photo luminescence spectrum, light output and decay kinetics of new samples are presented. Longitudinal uniformity of a sample of 22 radiation lengths is studied. Possible applications for calorimetry in high energy and nuclear physics experiments are discussed.