Search

We present a model of the ionization efficiency, or quenching factor, for low-energy nuclear recoils, based on a solution to Lindhard integral equation with binding energy and apply it to the calculation of the relative scintillation efficiency and charge yield for nuclear recoils in noble liquid detectors. The quenching model incorporates a constant average binding energy together with an electronic stopping power proportional to the ion velocity, and is an essential input in an analysis of charge recombination processes to predict the ionization and scintillation yields. Our results are comparable to NEST simulations of LXe and LAr and are in good agreement with available data. These studies are relevant to current and future experiments using noble liquids as targets for neutrino physics and the direct searches for dark matter., Comment: LIDINE2022 Conference Warsaw 22 Sep 2023

We present a study of the ionization efficiency in pure materials based on an extension of Lindhard’s original theory, in which the energy given to atomic motion by nuclear recoils is calculated taking into account a nonzero constant binding energy. We construct a modified integral equation that incorporates this effect consistently and find a numerical solution to this equation that leads to a ‘‘quenching factor’’ (QF) which is in good agreement with the available experimental measurements for Si and Ge. We argue that the model is a good approximation for Ge even for energies close to the true cutoff, while for Si is valid up to recoil energies greater than 500 eV. We also describe recent studies aimed at further extending the calculation of the QF for Si to even lower energies, relevant for current and future direct dark matter searches and the detection of coherent elastic scattering of neutrinos off nuclei.

arXiv:2011.12922v2, We present measurements of bulk radiocontaminants in the high-resistivity silicon CCDs from the DAMIC experiment at SNOLAB. We utilize the exquisite spatial resolution of CCDs to discriminate between α and β decays, and to search with high efficiency for the spatially-correlated decays of various radioisotope sequences. Using spatially-correlated β decays, we measure a bulk radioactive contamination of 32Si in the CCDs of 140 ± 30 μBq/kg, and place an upper limit on bulk 210Pb of < 160 μBq/kg. Using similar analyses of spatially-correlated α and β decays, we set upper limits of < 11 μBq/kg (0.9 ppt) on 238U and < 7.3 μBq/kg (1.8 ppt) on 232Th in the bulk silicon. The ability of DAMIC CCDs to identify and reject spatially-coincident backgrounds, particularly from 32Si, has significant implications for the next generation of silicon-based dark matter experiments, where β's from 32Si decay will likely be a dominant background., We are grateful to SNOLAB and its staff for support through underground space, logistical and technical services. SNOLAB operations are supported by the Canada Foundation for Innovation and the Province of Ontario Ministry of Research and Innovation, with underground access provided by Vale at the Creighton mine site. The CCD development work was supported in part by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We acknowledge financial support from the following agencies and organizations: National Science Foundation through Grant No. NSF PHY-1806974 and Kavli Institute for Cosmological Physics at The University of Chicago through an endowment from the Kavli Foundation; Fermi National Accelerator Laboratory (Contract No. DE-AC02-07CH11359); Institut Lagrange de Paris Laboratoire d’Excellence (under Reference No. ANR10-LABX-63) supported by French state funds managed by the Agence Nationale de la Recherche within the Investissements d’Avenir program under Reference No. ANR-11-IDEX-0004-02; Swiss National Science Foundation through Grant No. 200021 153654 and via the Swiss Canton of Zurich; Mexico’s Consejo Nacional de Ciencia y Tecnología (Grant No. 240666) and Direccíon General de Asuntos del Personal Académico–Universidad Nacional Autónoma de México (Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica Grants No. IB100413 and No. IN112213); STFC Global Challenges Research Fund (Foundation Awards Grant ST/R002908/1).

The CONNIE experiment is located at a distance of 30 m from the core of a commercial nuclear reactor, and has collected a 3.7 kg-day exposure using a CCD detector array sensitive to an $\sim$1 keV threshold for the study of coherent neutrino-nucleus elastic scattering. Here we demonstrate the potential of this low-energy neutrino experiment as a probe for physics Beyond the Standard Model, by using the recently published results to constrain two simplified extensions of the Standard Model with light mediators. We compare the new limits with those obtained for the same models using neutrinos from the Spallation Neutron Source. Our new constraints represent the best limits for these simplified models among the experiments searching for CE$\nu$NS for a light vector mediator with mass $M_{Z^{\prime}}, Comment: Accepted for publication in JHEP

We study the basic integral equation in Lindhard's theory describing the energy given to atomic motion by nuclear recoils in a pure material when the atomic binding energy is taken into account. The numerical solution, which depends only on the slope of the velocity-proportional electronic stopping power and the binding energy, leads to an estimation of the ionization efficiency which is in good agreement with the available experimental measurements for Si and Ge. In this model, the quenching factor for nuclear recoils features a cut-off at an energy equal to twice the assumed binding energy. We argue that the model is a reasonable approximation for Ge even for energies close to the cutoff, while for Si is valid up to recoil energies greater than ~500 eV., Comment: 10 pages, 7 figures

The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) uses low-noise fully depleted charge-coupled devices (CCDs) with the goal of measuring low-energy recoils from coherent elastic scattering (CE$\nu$NS) of reactor antineutrinos with silicon nuclei and testing nonstandard neutrino interactions (NSI). We report here the first results of the detector array deployed in 2016, considering an active mass 47.6 g (8 CCDs), which is operating at a distance of 30 m from the core of the Angra 2 nuclear reactor, with a thermal power of 3.8 GW. A search for neutrino events is performed by comparing data collected with reactor on (2.1 kg-day) and reactor off (1.6 kg-day). The results show no excess in the reactor-on data, reaching the world record sensitivity down to recoil energies of about 1 keV (0.1 keV electron-equivalent). A 95% confidence level limit for new physics is established at an event rate of 40 times the one expected from the standard model at this energy scale. The results presented here provide a new window to low-energy neutrino physics, allowing one to explore for the first time the energies accessible through the low threshold of CCDs. They will lead to new constrains on NSI from the CE$\nu$NS of antineutrinos from nuclear reactors., Comment: Updated to match the version accepted for publication in Physical Review D

Introduction/Background Ovarian cancer is the leading cause of death from gynecological cancer for women. The standard treatment consists of an extensive cytoreductive surgery followed with adjuvant chemotherapy. This study aims to identify the common postoperative complications as well as to define predictive factors of their occurrence. Methodology This study was conducted at Hotel-Dieu University Hospital in Lebanon between October 2017 and October 2018. All patients older than 18-year-old who underwent cytoredcutive surgery for ovarian cancer were followed up from the postoperative admission in the intensive care unit till discharge from hospital or at least for 30 days. Correlations between perioperative characteristics and complications were searched and analyzed. Results 40 patients were included. The mean age was 55 years old. The mean surgical complexity score was 5. Major complications have occurred in 32% of cases. They were associated with neoadjuvant chemotherapy (p=0.009), elevated surgical complexity (p=0.037), need for intraoperative transfusion and stay at intensive care unit more than 48 hours (p=0.05). Complications were infectious, hemodynamic, pulmonary, digestive and surgical. Need for parenteral nutrition was significantly correlated with longer operative time and neoadjuvant chemotherapy. No correlation was found between occurrence of complications and the following parameters: age, stage, APACHE II score, Charlston Comorbidity index and preoperative albuminemia. Conclusion Cancer stage, neoadjuvant chemotherapy, high surgical complexity, need for transfusions, delayed extubation and stay at intensive care unit more than 48 hours were predictive factors of higher postoperative morbidity in patients receiving cytoreductive surgery for ovarian cancer. Disclosure Nothing to disclose.

DAMIC Collaboration: et al., We report direct-detection constraints on light dark matter particles interacting with electrons. The results are based on a method that exploits the extremely low levels of leakage current of the DAMIC detector at SNOLAB of 2-6×10-22 A cm-2. We evaluate the charge distribution of pixels that collect, We acknowledge financial support from the following agencies and organizations: Kavli Institute for Cosmological Physics at The University of Chicago through an endowment from the Kavli Foundation; National Science Foundation through Grant No. NSF PHY-1806974; Mexico’s Consejo Nacional de Ciencia y Tecnología (Grant No. 240666) and Dirección General de Asuntos del Personal Academico—Universidad Nacional Autónoma de México (Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica Grant No. IN108917).

We present direct detection constraints on the absorption of hidden-photon dark matter with particle masses in the range 1.2-30 eV$c^{-2}$ with the DAMIC experiment at SNOLAB. Under the assumption that the local dark matter is entirely constituted of hidden photons, the sensitivity to the kinetic mixing parameter $\kappa$ is competitive with constraints from solar emission, reaching a minimum value of 2.2$\times$$10^{-14}$ at 17 eV$c^{-2}$. These results are the most stringent direct detection constraints on hidden-photon dark matter in the galactic halo with masses 3-12 eV$c^{-2}$ and the first demonstration of direct experimental sensitivity to ionization signals $, Comment: 5 pages, 5 figures

The CONNIE Experiment (Coherent Neutrino Nucleus Interaction Experiment) is currently collecting reactor neutrino data to search for the undiscovered standard model process of coherent neutrino-nucleus scattering (CNNS). The detector is composed of a silicon target of thick, fully-depleted, low-noise CCD detectors. Results from data collected in 2015 indicate backgrounds are controlled, and allow an estimate of sensitivity to be presented for a larger scale detector. A 2016 upgrade, adding additional target mass, and reducing readout noise, has been performed, increasing the total yield of signal events by a factor of 30, and already yielding science-quality data. Low-energy nuclear calibrations have been performed, enabling calibration down to the device energy threshold. An estimate of the sensitivity expected for measuring the coherent neutrino process is presented. Future prospects with improved detector energy thresholds are estimated.

We present measurements of radioactive contamination in the high-resistivity silicon charge-coupled devices (CCDs) used by the DAMIC experiment to search for dark matter particles. Novel analysis methods, which exploit the unique spatial resolution of CCDs, were developed to identify $\alpha$ and $\beta$ particles. Uranium and thorium contamination in the CCD bulk was measured through $\alpha$ spectroscopy, with an upper limit on the $^{238}$U ($^{232}$Th) decay rate of 5 (15) kg$^{-1}$ d$^{-1}$ at 95% CL. We also searched for pairs of spatially correlated electron tracks separated in time by up to tens of days, as expected from $^{32}$Si-$^{32}$P or $^{210}$Pb-$^{210}$Bi sequences of $\beta$ decays. The decay rate of $^{32}$Si was found to be $80^{+110}_{-65}$ kg$^{-1}$ d$^{-1}$ (95% CI). An upper limit of $\sim$35 kg$^{-1}$ d$^{-1}$ (95% CL) on the $^{210}$Pb decay rate was obtained independently by $\alpha$ spectroscopy and the $\beta$ decay sequence search. These levels of radioactive contamination are sufficiently low for the successful operation of CCDs in the forthcoming 100 g DAMIC detector., Comment: 18 pages, 20 figures

We introduce the fully-depleted charge-coupled device (CCD) as a particle detector. We demonstrate its low energy threshold operation, capable of detecting ionizing energy depositions in a single pixel down to 50 eVee. We present results of energy calibrations from 0.3 keVee to 60 keVee, showing that the CCD is a fully active detector with uniform energy response throughout the silicon target, good resolution (Fano ~0.16), and remarkable linear response to electron energy depositions. We show the capability of the CCD to localize the depth of particle interactions within the silicon target. We discuss the mode of operation and unique imaging capabilities of the CCD, and how they may be exploited to characterize and suppress backgrounds. We present the first results from the deployment of 250 um thick CCDs in SNOLAB, a prototype for the upcoming DAMIC100. DAMIC100 will have a target mass of 0.1 kg and should be able to directly test the CDMS-Si signal within a year of operation., 13 pages, 12 figures, proceedings prepared for 13th International Conference on Topics in Astroparticle and Underground Physics (TAUP2013)

The carbon -13 chemical shift of nine new substituted 2-amino benzothiazole is presented. The calculated chemical shift, using substituent parameters, agrees with the observed one.

DAMIC (Dark Matter in CCDs) is an experiment searching for dark matter particles employing fully-depleted charge-coupled devices. Using the bulk silicon which composes the detector as target, we expect to observe coherent WIMP-nucleus elastic scattering. Although located in the SNOLAB laboratory, 2 km below the surface, the CCDs are not completely free of radioactive contamination, in particular coming from radon daughters or from the detector itself. We present novel techniques for the measurement of the radioactive contamination in the bulk silicon and on the surface of DAMIC CCDs. Limits on the Uranium and Thorium contamination as well as on the cosmogenic isotope 32 Si, intrinsically present on the detector, were performed. We have obtained upper limits on the 238 TJ (232 Th) decay rate of 5 (15) kg_1 d_1 at 95% CL. Pairs of spatially correlated electron tracks expected from 32 Si-32 P and 210 Pb-210 Bi beta decays were also measured. We have found a decay rate of 80+l10 -65 kg_1 d_1 for 32 Si and an upper limit of - 35 kg-1 d-1 for 210 Pb, both at 95% CL.

We show that it is possible to use Taylor series approximations to numerically find scaling functions associated with the Julia sets of complex maps. The example we use is the mapping z → z 2 + c . The Taylor series are in powers of the parameter c about the trivial case c =0.

A retrospective study was conducted to determine the influence of the acquired immunodeficiency syndrome (AIDS) epidemic on the incidence, clinical presentation, and outcome of primary gastrointestinal lymphoma (stages I and II) over a 20-year period at a single institution. Between 1971 and 1981, there were seven cases. Fifty-eight patients were diagnosed between 1983 and 1993, and 81 per cent were AIDS-related. The mean age overall was 50 years; 81 per cent were male, and 35 per cent presented with acute complications. All tumors were high or intermediate grade B cell lymphomas, and 48 per cent had bulky or advanced disease at presentation. The overall actuarial 5-year survival was 9 per cent. Human immunodeficiency virus status and stage were significant independent prognostic factors. The AIDS-related subgroup had a mean age of 43 years, and 91 per cent were male. Tumor resection was performed in 38 per cent, and the 5-year survival was 2 per cent. The mean age for the non-AIDS-related subgroup was 71 years, and 55 per cent were male. Resection was performed in 39 per cent, and 5-year survival was 28 per cent. AIDS-related disease accounted for the dramatic increase in incidence of primary gastrointestinal lymphoma since 1983. The prognosis for these patients is poor and is dominated by the underlying immunocompromise.

Previous reports evaluating appendicitis in patients with human immunodeficiency virus/ acquired immunodeficiency syndrome have detailed unusual pathology, atypical clinical presentations, and poor outcomes. These reports have described small groups of patients and are inconsistent with larger surveys.A retrospective design was used to evaluate patients diagnosed with human immunodeficiency virus or acquired immunodeficiency syndrome undergoing appendectomy from 1986 to 1995.Fifty-five patients were evaluated (mean age 33.4 +/- 8.2 years, 98 percent male, 90 percent clinical acquired immunodeficiency syndrome, CD4 count 144.45 +/- 34 cells/mL3). Presenting symptoms included right lower quadrant pain (91 percent), nausea and vomiting (41 percent), diarrhea (22 percent), and generalized abdominal pain (24 percent). Significant findings on examination included right lower quadrant tenderness (91 percent), rebound (74 percent), fever (54 percent), abdominal distention (7 percent), and generalized abdominal tenderness (9.3 percent). Computed tomography was performed in 26 percent and findings were suggestive of appendicitis in 93 percent of cases. Operative findings included acute inflammation (83.3 percent), appendiceal rupture (24 percent), gangrene (29 percent), and normal-appearing appendices (5.5 percent). Unusual findings included Mycobacterium tuberculosis (1.8 percent), atypical mycobacterium (1.8 percent), and chronic appendicitis (3.7 percent). Thirty-day survival was 100 percent. Significant postoperative fevers were noted in 33 percent and lasted 4.63 +/- 1.2 days. The presence of prolonged postoperative fever was linked to lower CD4 counts (p = .05). Follow-up (mean time to follow-up, 1,656 +/- 970 days) was complete in 43 percent. Survival at follow-up was noted in 57.1 percent (mean length of survival after surgery, 837 +/- 155 days).Appendectomy in patients with human immunodeficiency virus/acquired immunodeficiency syndrome is associated with little morbidity or mortality. Atypical pathology is rarely identified. A higher than expected rate of rupture may be linked to delays before hospitalization or to impaired immune status.

Hepatobiliary disease is a common manifestation of acquired immunodeficiency syndrome, although the role of surgical intervention in the spectrum of therapy is unclear.A retrospective review was designed to evaluate the characteristics of patients given a diagnosis of human immunodeficiency virus infection or acquired immunodeficiency syndrome and undergoing cholecystectomy between January 1, 1986, and November 1, 1995.The study included 40 patients (35 men, 5 women; mean age, 42 +/- 9 years), 33 (82.5 percent) with acquired immunodeficiency syndrome; their mean preoperative T-helper (CD4) cell count was 163/mL3. Gross pathologic findings included acute (n = 9, 22.5 percent) and chronic (n = 31, 77.5 percent) cholecystitis. Gallbladder specimens were positive for cholelithiasis in 28 (70 percent), Cryptococcus organisms in 5 (12.5 percent), cytomegalovirus in 3 (7.5 percent), and lymphoma in 2 (5 percent). The median follow-up time was 48 months (range, 6 to 63 months). The percentage survival was 92.5 percent (n = 37) at 30 days, and 57.5 percent (n = 23), 37.5 percent (n = 15), and 25 percent (n = 10) at 12, 24, and 36 months, respectively. The mean survival time was 25.1 months. The likelihood of survival was directly linked to the CD4 cell count. The mean survival period was 25 months for patients with CD4 cell counts less than 200/mL3 compared with 48 months for those with CD4 cell counts greater than 200/mL3.Although the pathologic changes identified in patients with acquired immunodeficiency syndrome may occasionally be atypical, the clinical presentation, indications for operation, and pathologic findings identified are quite common. Patients tolerate cholecystectomy well with good long-term outcome and minimal infectious complications. Even in patients with the most compromised immune status, a 2-year survival after operation is acceptable. Cholecystectomy has a clear role in the spectrum of treatment for biliary disease relative to acquired immunodeficiency syndrome.

A series of N-substituted 2-aminobenzothiazoles, 2-aminothiazolopyridines, and 2-aminothiazoloquinolines were prepared by the cyclization of N,N'-disubstituted thiourea derivatives by bromine in acetic acid. The uv, ir and nmr data for these compounds are presented and discussed.

Thirty-six new N,N'-disubstituted thioureas have been synthesized by the reaction of phenyl-, p-fluorophenyl- and benzoylisothiocyanates with various substituted anilines, aminopyridines and 4-aminoquinolines. The uv, ir and nmr spectral data are presented and discussed.

The authors numerically determine the f( alpha ) spectrum of scaling indices for critical KAM tori in the area-preserving standard map. Similarities and differences between the corresponding orbits of circle maps are discussed.

relative oximation rates of the various class members. Every alkanone (except 2-propanone, 2-butanone, and 3-pentanone) may be assigned to one of the 25 classes listed in Table I . According to Rule I the oximation rate of a given alkanone would be the same or lower than the rate of the first member of the class to which it has been assigned. The reactivity of a given class would therefore be defined if class members of increasing branching were prepared and tested until an alkanone of low reactivity was found. This was easily and completely realized for classes A l l , A12, Bs, Cq, Cg, E, and F and partially realized for classes Ag, Ala, B2-B4, c1-c3, and D. The alkanones nones in class B1 roughly parallel the corresponding members of class B2 (Rule I l l -D) . The remaining classes A1-As are generally very reactive and therefore represent the greatest area of uncertainty.

The magnetic shielding of nuclei due to distant chemical groups may be calculated from the knowledge of the magnetic anisotropy of the bonds in these groups. The reverse procedure, namely, the calculation of the magnetic anisotropy of bonds from NMR relative chemical shifts has been employed here to estimate the magnetic anisotropy of −C≡C, −C≡N, and −N≡C triple bonds. The paramagnetic contribution to the shielding of the acetylenic proton was estimated from the calculated value of ΔχC≡C, and from the known geometry of the molecule. The value thus obtained is compared with that calculated by quantum mechanical methods.

Six substituted 6H-indolo[2,3-b]quinoxalines were synthesized by the interaction o-phenyl-enediamine with substituted isatins. The uv, ir and nmr spectral data for the compounds synthesized are presented and discussed.

Department of Chemistry. College of Science, University of Baghdad, Baghdad, Iraq. Manuscript received 20 December 1974 ; accepted 22 November 1975 Studies in Nuclear Magnetic Resonance. The Kinetics of Protonation of Aliphatic Amines.

Department of Chemistry, College of Sciences, Adhamiya, Iraq Manuscript received 30 August 1972; accepted 5 July 1973 The NMR method has been used to determine the association constants of some pyridines and quinolines with 1,3,5-trinitrobenzene in carbon-tetrachloride. Also, the detennination of some thermodynamic parameters for the association of 2-methylindole with 1,3,5-trinitrobenzene is made.