Implications of the SNO and the Homestake Results for the BOREXINO Experiment

Using the recent result of the SNO solar neutrino experiment, we have demonstrated in a model independent way that the contribution of Be-7 and other medium energy neutrinos to the event rate of the Homestake experiment is 4 sigma smaller than the BP2000 SSM prediction. We have considered the implications of this result for the future BOREXINO experiment.Comment: 9 pages, no figure

An in vitro system for the comparison of excision and wet-dry swabbing for microbiological sampling of beef carcasses.

An in vitro system for the comparison of wet-dry swabbing and surface tissue excision was developed to ascertain whether the commonly accepted statement of the advantage (in terms of bacterial recovery) of the tissue excision method is also legitimate when different kinds of bacteria are used. A total of 1,770 sections (2.5 by 10 cm) of bovine skin were individually inoculated on the subcutaneous fat side by spreading various suspensions of marker organisms (nalidixic acid-resistant Escherichia coli, vancomycin-resistant Enterococcus faecalis, and methicillin-resistant Staphylococcus aureus) at different concentrations and sampled by two standard methods: cotton wet-dry swabbing and excision. Most counts from cuts sampled by excision were significantly (P < 0.05) higher than the wet-dry swabs; however, no differences were observed between the control and the sampling method when sections were inoculated with bacterial solutions at a concentration of 10(3) CFU/ml and sampled by excision. For sections inoculated with bacterial solutions at a concentration of 10(3) CFU/ml, counts given as log CFU/25 cm2 ranged from 1.97 (S. aureus sampled by wet-dry swab) to 3.06 (S. aureus sampled by excision). For sections inoculated at a concentration of 10(4), counts given as log CFU/25 cm(2) ranged from 2.15 (E. faecalis sampled by wet-dry swab) to 3.19 (S. aureus sampled by excision). For sections inoculated at 10(5), counts given as log CFU/25 cm(2) ranged from 2.94 (E. faecalis, wet-dry swab) to 3.98 (S. aureus, excision), and for sections inoculated at 106, counts given as log CFU/25 cm(2) ranged from 3.53 (E. coli, wet-dry swab) to 4.69 (S. aureus, excision). The proposed system, which enabled a considerable amount of samples to be analyzed under controlled experimental conditions and a large number of data to be generated in a short time, demonstrated among the tested microorganisms that whereas the excision method recovered the highest number of bacteria, control means were always (with the exception of an inoculum of 10(3)/ml) significantly higher than means from either of the sampling methods. Our results indicate that particular attention should be paid to the diverse microflora that can contaminate carcasses in a given slaughterhouse and that it is not appropriate to generalize by saying that the destructive method is the reference technique for the bacteriological sampling of carcasses in slaughterhouses, especially when the contamination is higher than 10(3) CFU/25 cm(2)

QED Corrections to the Scattering of Solar Neutrinos and Electrons

We discuss recent calculations of the O(alpha) QED corrections to the recoil electron energy spectrum in neutrino electron scattering, and to the spectrum of the combined energy of the recoil electron and a possible accompanying photon emitted in the scattering process. We then examine the role of these corrections in the interpretation of precise measurements from solar neutrino electron scattering experiments.Comment: (16 Pages, 4 Figures) Presented at the Symposium in Honor of Professor Alberto Sirlin's 70th Birthday: ``50 Years of Precision Electroweak Physics'', New York University, October 27-28, 200

QED Corrections to Neutrino Electron Scattering

We evaluate the O(alpha) QED corrections to the recoil electron energy spectrum in the process nu_l + e --> nu_l + e (+gamma), where (+gamma) indicates the possible emission of a photon and l=e, mu or tau. The soft and hard bremsstrahlung differential cross sections are computed for an arbitrary value of the photon energy threshold. We also study the O(alpha) QED corrections to the differential cross section with respect to the total combined energy of the recoil electron and a possible accompanying photon. Their difference from the corrections to the electron spectrum is investigated. We discuss the relevance and applicability of both radiative corrections, emphasizing their role in the analysis of precise solar neutrino electron scattering experiments.Comment: 14 pages + 10 figures. Minimal changes, published versio

Pulse-Shape discrimination with the Counting Test Facility

Pulse shape discrimination (PSD) is one of the most distinctive features of liquid scintillators. Since the introduction of the scintillation techniques in the field of particle detection, many studies have been carried out to characterize intrinsic properties of the most common liquid scintillator mixtures in this respect. Several application methods and algorithms able to achieve optimum discrimination performances have been developed. However, the vast majority of these studies have been performed on samples of small dimensions. The Counting Test Facility, prototype of the solar neutrino experiment Borexino, as a 4 ton spherical scintillation detector immersed in 1000 tons of shielding water, represents a unique opportunity to extend the small-sample PSD studies to a large-volume setup. Specifically, in this work we consider two different liquid scintillation mixtures employed in CTF, illustrating for both the PSD characterization results obtained either with the processing of the scintillation waveform through the optimum Gatti's method, or via a more conventional approach based on the charge content of the scintillation tail. The outcomes of this study, while interesting per se, are also of paramount importance in view of the expected Borexino detector performances, where PSD will be an essential tool in the framework of the background rejection strategy needed to achieve the required sensitivity to the solar neutrino signals.Comment: 39 pages, 17 figures, submitted to Nucl. Instr. Meth.

Likelihood scan of the Super-Kamiokande I time series data

In this work a detailed spectral analysis of the time series of the 8B solar neutrino flux published by the Super-Kamiokande Collaboration is presented, performed through a likelihood scan approach. Preliminarily a careful review of the analysis methodology is given, showing that the traditional periodicity search via the Lomb-Scargle periodogram is a special case of a more general likelihood based method. Since the data are published together with the relevant asymmetric errors, it is then shown how the likelihood analysis can be performed either with or without a prior error averaging. A key point of this work is the detailed illustration of the mathematical model describing the statistical properties of the estimated spectra obtained in the various cases, which is also validated through extensive Monte Carlo computations; the model includes a calculation for the prediction of the possible alias effects. In the successive investigation of the data, such a model is used to derive objective, mathematical predictions which are quantitatively compared with the features observed in the experimental spectra. This article clearly demonstrates that the handling of the errors is the origin of the discrepancy between published null observations and claimed significant periodicity in the same SK-I data sample. Moreover, the comprehensive likelihood analysis with asymmetric errors developed in this work provides results which cannot exclude the null hypothesis of constant rate, even though some indications stemming from the model at odd with such conclusion point towards the desirability of additional investigations with alternative methods to shed further light on the characteristics of the data.Comment: 49 pages, 38 figures. Calculation of the asymmetric likelihood revised. Accepted fo publication on Physical Review

Constraining Majorana neutrino electromagnetic properties from the LMA-MSW solution of the solar neutrino problem

In this paper we use solar neutrino data to derive stringent bounds on Majorana neutrino transition moments (TMs). Should such be present, they would contribute to the neutrino--electron scattering cross section and hence alter the signal observed in Super-Kamiokande. Motivated by the growing robustness of the LMA-MSW solution of the solar neutrino problem indicated by recent data, and also by the prospects of its possible confirmation at KamLAND, we assume the validity of this solution, and we constrain neutrino TMs by using the latest global solar neutrino data. We find that all elements of the TM matrix can be bounded at the same time. Furthermore, we show how reactor data play a complementary role to the solar neutrino data, and use the combination of both data sets to improve the current bounds. Performing a simultaneous fit of LMA-MSW oscillation parameters and TMs we find that 6.3 times 10^{-10} mu_B and 2.0 times 10^{-10} mu_B are the 90% C.L. bounds from solar and combined solar + reactor data, respectively. Finally, we perform a simulation of the upcoming Borexino experiment and show that it will improve the bounds from today's data by roughly one order of magnitude.Comment: Latex, 24 pages, 6 figures; misprints correcte

Superheated Microdrops as Cold Dark Matter Detectors

It is shown that under realistic background considerations, an improvement in Cold Dark Matter sensitivity of several orders of magnitude is expected from a detector based on superheated liquid droplets. Such devices are totally insensitive to minimum ionizing radiation while responsive to nuclear recoils of energies ~ few keV. They operate on the same principle as the bubble chamber, but offer unattended, continuous, and safe operation at room temperature and atmospheric pressure.Comment: 15 pgs, 4 figures include

ASL expression in ALDH1A1+ neurons in the substantia nigra metabolically contributes to neurodegenerative phenotype

Argininosuccinate lyase (ASL) is essential for the NO-dependent regulation of tyrosine hydroxylase (TH) and thus for catecholamine production. Using a conditional mouse model with loss of ASL in catecholamine neurons, we demonstrate that ASL is expressed in dopaminergic neurons in the substantia nigra pars compacta, including the ALDH1A1 + subpopulation that is pivotal for the pathogenesis of Parkinson disease (PD). Neuronal loss of ASL results in catecholamine deficiency, in accumulation and formation of tyrosine aggregates, in elevation of α-synuclein, and phenotypically in motor and cognitive deficits. NO supplementation rescues the formation of aggregates as well as the motor deficiencies. Our data point to a potential metabolic link between accumulations of tyrosine and seeding of pathological aggregates in neurons as initiators for the pathological processes involved in neurodegeneration. Hence, interventions in tyrosine metabolism via regulation of NO levels may be therapeutic beneficial for the treatment of catecholamine-related neurodegenerative disorders