36815013
Prospects of gravitational wave data mining and exploration via evolutionary computing
Techniques of evolutionary computing have proven useful for a diverse array of fields in science and engineering. Because of the expected low signal to noise ratio of LIGO data and incomplete knowledge of gravitational waveforms, evolutionary computing is an excellent candidate for LIGO data analysis studies. Using the evolutionary computing methods of genetic algorithms and genetic programming, we have developed, as a proof of principle, search algorithms that are effective at finding sine-gaussian signals hidden in noise while maintaining a small false alarm rate. Because we used realistic LIGO noise as a training ground, the algorithms we have evolved should be well suited to detecting signals in actual LIGO data, as well as in simulated noise. These algorithms have continuously improved during the five days of their evolution and are expected to improve further the more they are evolved. The top performing algorithms from generation 100 and 199 were benchmarked using gaussian white noise to illustrate their performance and the improvement over 100 generations.
26319866
Accurate calibration of test mass displacement in the LIGO interferometers
We describe three fundamentally different methods we have applied to calibrate the test mass displacement actuators to search for systematic errors in the calibration of the LIGO gravitational-wave detectors. The actuation frequencies tested range from 90 Hz to 1 kHz and the actuation amplitudes range from 10−6 m to 10−18 m. For each of the four test mass actuators measured, the weighted mean coefficient over all frequencies for each technique deviates from the average actuation coefficient for all three techniques by less than 4%. This result indicates that systematic errors in the calibration of the responses of the LIGO detectors to differential length variations are within the stated uncertainties.
117574348
Excluding Source Models with Multiple Astrophysical Observations
We describe a general method to observationally exclude a theoretical model for gravitational wave (GW) emission from a transient astrophysical source (event) by using a null detection from a network of GW detectors. In the case of multiple astrophysical events with no GW detection, statements about individual events can be combined to increase the exclusion confidence. We frame and demonstrate the method using a population of hypothetical core collapse supernovae.
14181827
Search method for unmodeled transient gravitational waves associated with SGR flares
We describe a method for searching for transient gravitational waves associated with soft gamma-ray repeater (SGR) flares or other burst-like events using data collected by interferometric gravitational wave detectors. The method can be used to analyze data from either a single detector or from two detectors coherently. The excess power-type algorithm creates event sets from conditioned detector data which may be compared to signal simulations of known strength based on plausible waveform classes. Estimated search sensitivities obtained by performing two-detector searches on the simulated data are presented. In the case of 22 ms duration white noise bursts in the 100–200 Hz band injected into simulated noise, we find a characteristic strain sensitivity h90%rss = 3.0 × 10−22 .
118446989
Stacking gravitational wave signals from soft gamma repeater bursts
Soft gamma repeaters (SGRs) have unique properties that make them intriguing targets for gravitational wave (GW) searches. They are nearby, their burst emission mechanism may involve neutron star crust fractures and excitation of quasinormal modes, and they burst repeatedly and sometimes spectacularly. A recent LIGO search for transient GW from these sources placed upper limits on a set of almost 200 individual SGR bursts. These limits were within the theoretically predicted range of some models. We present a new search strategy which builds upon the method used there by “stacking” potential GW signals from multiple SGR bursts. We assume that variation in the time difference between burst electromagnetic emission and burst GW emission is small relative to the GW signal duration, and we time-align GW excess power time-frequency tilings containing individual burst triggers to their corresponding electromagnetic emissions. Using Monte Carlo simulations, we confirm that gains in GW energy sensitivity of N^(1/2) are possible, where N is the number of stacked SGR bursts. Estimated sensitivities for a mock search for gravitational waves from the 2006 March 29 storm from SGR 1900+14 are also presented, for two GW emission models, “fluence-weighted” and “flat” (unweighted).
14925786
Benefits of artificially generated gravity gradients for interferometric gravitational-wave detectors
We present an approach to experimentally evaluate gravity gradient noise, a potentially limiting noise source in advanced interferometric gravitational-wave detectors. In addition, the method can be used to provide sub-percent calibration in phase and amplitude. Knowledge of calibration to such certainties shall enhance the scientific output of the instruments in the case of an eventual detection of gravitational waves. The method relies on a rotating symmetrical two-body mass, a dynamic gravity field generator (DFG). The placement of the DFG in the proximity of one of the interferometer's suspended test masses generates a change in the local gravitational field detectable with current interferometric gravitational-wave detectors.
124176528
Wide-angle proton-proton elastic scattering from 1.3 to 3.0 GeV/c
SummaryDifferential cross-sections for proton-proton elastic scattering have been measured covering the angular range from 50° to 90° c.m. at twelve incident momenta from 1.3 to 3.0 GeV/c. The angular distributions are quite smooth, but there is evidence of structure in the energy dependence of fixed-angle cross-sections at |t| ∼ 1 (GeV)2.RiassuntoSi sono misurate le sezioni d’urto differenziali per lo scattering elastico protone-protone coprendo l’intervallo angolare da 50° a 90° c.m. a dodici impulsi incidenti da 1.3 a 3.0 GeV/c. Le distribuzioni angolari sono abbastanza lineari, ma si hanno prove di una struttura nella dipendenza dell’energia dalle sezioni d’urto ad angolo fisso per |t| ∼ 1 (GeV)2.РеэюмеБыли иэмерены дифференциальные поперечные сечения протон-протонного упругого рассеяния в области углов от 50° до 90° в системе центра масс при двенадцати эначениях начальных импульсов от 1.3 до З.ОГзВ/с. Угловые распределения являются довольно плавными, но обнаружена структура в знергетической эависимости поперечных сечений при фиксированном угле при |t| ∼ 1 (ГзВ)2.
123331390
Experimental techniques in particle physics
Abstract The great majority of experiments in particle physics use beams of particles from accelerators. Individual interactions of these with other particles are observed by detector systems. Fixed target and colliding beam experiments are contrasted, and non-accelerator experiments mentioned briefly. An account is given of the principles of the various detectors. These include scintillation and Cerenkov counters and the various tracking devices such as bubble chambers, proportional and drift chambers. Calorimeters have emerged recently as important detectors at the highest energies. Electronic logic modules are mentioned and the main steps in data acquisition and analysis are described. Finally an example is given of a large detector system.
121760874
Some Hadron Calorimeter Properties Relevant to Storage Rings
At wide angles in a storage ring environment, a substantial part of the energy seen by a hadron calorimeter can be in the form of very low momentum particles such as jet fragments or resonance cascade decay products. Data are presented on the deviations from Gaussian resolution and linear response for such low momentum particles. The differing responses to incident e-, μ-, π+-, K+-, p and at momenta below 10 GeV/c are also compared. In addition, we discuss the significance of angle effects for a 4π calorimeter, and the problems of combining data from calorimeters with different physical characteristics. Experimental data are presented on the difference in hadron response between a fine grain ("electromagnetic") lead calorimeter and a coarser ("hadron") iron calorimeter, and on the dependence of the response on the energy sharing between the two calorimeters.
117258763
A study of nucleon isobar production in proton-proton collisions
SummaryThe momentum spectra of protons scattered inelastically in proton-proton collisions were obtained in an external beam at NIMROD, using incident-proton momenta of 2.85, 4.55, 6.06 and 7.88 GeV/c, and various scattering angles in the range 22 to 144 mrad. The isobars of mass 1236, 1518 and 1688 MeV are clearly seen. There is evidence also in the spectra at small angles for the production of the 1410 MeV isobar at a mass of (1410±15) MeV and width (125±20) MeV. It is shown that the observed peak cannot be explained by the Deck effect. The differential cross-sections for the production of these isobars are presented in terms of the usual variabless andt, and are compared with absorption and Regge-pole model predictions. Fits to the data with various empirical functions of these variables are also investigated. The behaviour of the total cross-section for the 1236 MeV isobar is found to exhibit energy-dependence consistent with one-pion exchange, whereas the 1410 MeV and 1688 MeV isobar total cross-sections are found to be energy-independent. Also the total cross-section for the 1518 MeV isobar is found to exhibit energy-dependence in this energy range.RiassuntoSi sono ottenuti gli spettri delle quantità di moto dei protoni diffusi anelasticamente nelle collisioni protone-protone ottenute in un raggio esterno di NIMROD, usando quantità di moto del protone incidente di 2.85, 4.55, 6.06 e 7.88 GeV/c, e vari angoli di scattering da 22 a 144 mrad. Si vedono chiaramente gli isobari di massa 1236, 1518 e 1688 MeV. Si hanno anche prove negli spettri a piccoli angoli della produzione dell’isobaro da 1410 MeV di massa (1410±15) MeV e ampiezza (125±20) MeV. Si dimostra che il picco osservato non può essere spiegato con l’effetto Deck. Si presentano le sezioni d’urto differenziali per la produzione di questi isobari in funzioni delle usuali variabilis et, e si confrontano con le previsioni del modello dei poli di Regge e del modello di assorbimento. Si studiano anche le approssimazioni ai dati con varie funzioni empiriche di queste variabili. Si trova che il comportamento della sezione d’urto totale per l’isobaro da 1236 MeV presenta una dipendenza dall’energia che concorda con lo scambio di un pione, mentre le sezioni d’urto degli isobari da 1410 MeV e 1688 MeV risultano indipendenti dall’energia. Si trova che anche la sezione d’urto totale presenta una dipendenza dall’energia in questo intervallo di energie.РеэумеПолучаются импульсные спектры протонов, неупруго рассеянных в протон-протонных соударениях во внещнем пучке в HИMPOД, испольэуя импульсы падаюших протонов 2.85, 4.55, 6.06 и 7.88 ГЭB/c, и раэличные углы рассеяния в области от 22 до 144 миллирадиан. Четко видны иэобары с массами 1236, 1518 и 1688 MЭB. Также имеется подтверждение в спектрах при малых углах для рождения иэобары 1410 MЭB с массой (1410±15) MЭB и щириной (125±20) MЭB. Покаэывается, что наблюденный пик не может быть общяснен с помошью Эффекта Дека. Представлены дифференциальные поперечные сечения для рождения Этих иэобар в терминах обычных переменныхs иt, которые сравниваются с предскаэаниями моделей поглошения и полюсов Редже. Также исследуются подгонки для Этих данных с помошью раэличных Эмпирических функций Этих переменных. Найдено, что поведение полного поперечного сечения для иэобары 1236 MЭB обнаруживает Энергетическую эависимость, согласуюшуюся с одно-пионным обменом, в то зе время получено, что полные поперечные сечения иэобар 1410 MЭB и 1688 MЭB не эависят от Энергии. Также найдено, что полное поперечное сечение для иэобары 1518 MЭB обнаруживает эависимость от Энергии в Этой области Энергий.
123687310
Antiproton--proton annihilation into charged pion and kaon pairs
Events of the type anti pp $Yields$ K$sup -$K$sup +$, $pi$$sup - $$pi$$sup +$ were studied at 0.79 to 2.43 GeV/c. Differential cross sections and Legendre coefficient ratios are shown. Resonances found as a result of model fitting showing spin--parity assignment versus mass squared are also shown. (JFP)