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Rajendran Raja

Publications and source records attributed to Rajendran Raja.

18 recordsLinked to original sources
arXiv2013

Particle Production Measurements using the MIPP Detector at Fermilab

The Main Injector Particle Production (MIPP) experiment is a fixed target hadron production experiment at Fermilab. It measures particle production in interactions of 120 GeV/c primary protons from the Main Injector and secondary beams of $π^{\pm}, \rm{K}^{\pm}$, p and $\bar{\rm{p}}$ from 5 to 90 GeV/c on nuclear targets which include H, Be, C, Bi and U, and a dedicated run with the NuMI target. MIPP is a high acceptance spectrometer which provides excellent charged particle identification using Time Projection Chamber (TPC), Time of Flight (ToF), multicell Cherenkov (CKOV), Ring Imaging Cherenkov (RICH) detectors, and Calorimeter for neutrons. We present inelastic cross section measurements for 58 and 85 GeV/c p-H interactions, and 58 and 120 GeV/c p-C interactions. A new method is described to account for the low multiplicity inefficiencies in the interaction trigger using KNO scaling. Inelastic cross sections as a function of multiplicity are also presented. The MIPP data are compared with the Monte Carlo predictions and previous measurements. We also describe an algorithm to identify charged particles ($π^{\pm}/\rm{p}/\bar{\rm{p}}$ etc.), and present the charged pion and kaon spectra from the interactions of 120 GeV/c protons with carbon target.

hep-ex↗
arXiv2013

The Case for a Muon Collider Higgs Factory

We propose the construction of a compact Muon Collider Higgs Factory. Such a machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean Higgs events per year, enabling the most precise possible measurement of the mass, width and Higgs-Yukawa coupling constants.

hep-ph↗
arXiv2007

An experimental program for demonstrating precision jet energy measurement at the ILC

We outline a physics program at Fermilab that would significantly improve our ability to understand the behavior of hadronic showers in calorimeters. This would involve a two-pronged approach designed to measure particle production cross sections of hadronic beams on several nuclei to improve shower simulation programs and the validation of the improved shower simulation predictions using test beams (including tagged neutral beams) in which calorimeter modules built using various technologies are deployed in the test beam. Such a program would be of immediate benefit to the efforts to design and build optimal calorimeters for the International Linear Collider.

physics.ins-det↗
arXiv2007

Tagged Neutron, Anti-neutron and K-Long beams in an Upgraded MIPP Spectrometer

The MIPP experiment operating with an upgraded data acquisition system will be capable of acquiring data at the rate of 3000 events per second. Currently we are limited to a rate of 30 Hz due to the bottlenecks in the data acquisition electronics of the Time Projection Chamber (TPC). With the speeded up DAQ, MIPP will be capable of acquiring data at the rate of $\approx$5 million events per day. This assumes a conservative beam duty cycle of 4~sec spill every 2 minutes with a 42% downtime for main injector beam manipulations for the $\bar{p}$ source. We show that such a setup is capable of producing tagged neutron, anti-neutron and $K^0_L$ beams that are produced in the MIPP cryogenic hydrogen target using proton, anti-proton and $K^{\pm}$ beams. These tagged beams can be used to study calorimeter responses for use in studies involving the Particle Flow Algorithm (PFA). The energy of these tagged beams will be known to better than 2% on a particle by particle level by means of constrained fitting. We expect a tagged beam rate in the tens of thousands a day. The MIPP spectrometer thus offers a unique opportunity to study the response of calorimeters to neutral particles.

hep-ex↗
arXiv2006

The Main Injector Particle Physics Experiment (MIPP FNAL E-907) at Fermilab - status and plans

We describe the status of the Main Injector particle production Experiment (MIPP) at Fermilab which has to date acquired 18 million events of particle interactions using (5 GeV/c-120 GeV/c) $π^\pm, K^\pm$ and $p^\pm$ beams on various targets. We describe plans to upgrade the data acquisition speed of MIPP to make it run 100 times faster which will enable us to obtain particle production data of unprecdented quality and statistics on a wide variety of nuclear targets including nitrogen which is of importance to cosmic ray physics.

hep-ex↗
arXiv2006

A General Theory of Goodness of Fit in Likelihood Fits

Maximum likelihood fits to data can be performed using binned data and unbinned data. The likelihood fits in either case produce only the fitted quantities but not the goodness of fit. With binned data, one can obtain a measure of the goodness of fit by using the $χ^2$ method, after the maximum likelihood fitting is performed. With unbinned data, currently, the fitted parameters are obtained but no measure of goodness of fit is available. This remains, to date, an unsolved problem in statistics. By considering the transformation properties of likelihood functions with respect to change of variable, we conclude that the likelihood ratio of the theoretically predicted probability density to that of {\it the data density} is invariant under change of variable and provides the goodness of fit. We show how to apply this likelihood ratio for binned as well as unbinned likelihoods and show that even the $χ^2$ test is a special case of this general theory. In order to calculate errors in the fitted quantities, we need to solve the problem of inverse probabilities. We use Bayes' theorem to do this, using the data density obtained in the goodness of fit. This permits one to invert the probabilities without the use of a Bayesian prior. The resulting statistics is consistent with frequentist ideas.

physics.data-an↗
arXiv2005

The Main Injector Particle Production Experiment (MIPP) at Fermilab

We describe the physics capabilites and status of the MIPP experiment which is scheduled to enter its physics data taking period during December 2004-July 2005. We show some of the results obtained from the engineering run that concluded in August 2004 and point out the unique features that make it an ideal apparatus to study non-perturbative QCD properties.

hep-ex↗
arXiv2004

Status of Neutrino Factory R&D within the Muon Collaboration

We describe the current status of the research within the Muon Collaboration towards realizing a Neutrino Factory. We describe briefly the physics motivation behind the neutrino factory approach to studying neutrino oscillations and the longer term goal of building the Muon Collider. The benefits of a step by step staged approach of building a proton driver, collecting and cooling muons followed by the acceleration and storage of cooled muons are emphasized. Several usages of cooled muons open up at each new stage in such an approach and new physics opportunites are realized at the completion of each stage.

hep-ex↗
arXiv2004

A Measure of the Goodness of Fit in Unbinned Likelihood Fits; End of Bayesianism?

Maximum likelihood fits to data can be done using binned data (histograms) and unbinned data. With binned data, one gets not only the fitted parameters but also a measure of the goodness of fit. With unbinned data, currently, the fitted parameters are obtained but no measure of goodness of fit is available. This remains, to date, an unsolved problem in statistics. Using Bayes' theorem and likelihood ratios, we provide a method by which both the fitted quantities and a measure of the goodness of fit are obtained for unbinned likelihood fits, as well as errors in the fitted quantities. The quantity, conventionally interpreted as a Bayesian prior, is seen in this scheme to be a number not a distribution, that is determined from data.

physics.data-an↗
arXiv2002

A Measure of the Goodness of Fit in Unbinned Likelihood Fits

Maximum likelihood fits to data can be done using binned data (histograms) and unbinned data. With binned data, one gets not only the fitted parameters but also a measure of the goodness of fit. With unbinned data, currently, the fitted parameters are obtained but no measure of goodness of fit is available. This remains, to date, an unsolved problem in statistics. Using Bayes theorem and likelihood ratios, we provide a method by which both the fitted quantities and a measure of the goodness of fit are obtained for unbinned likelihood fits, as well as errors in the fitted quantities. We provide an ansatz for determining Bayesian a priori probabilities.

physics.data-an↗
arXiv2002

Confidence Limits and their Robustness

Confidence limits are common place in physics analysis. Great care must be taken in their calculation and use, especially in cases of limited statistics when often one-sided limits are quoted. In order to estimate the stability of the confidence levels to addition of more data and/or change of cuts, we argue that the variance of their sampling distributions be calculated in addition to the limit itself. The square root of the variance of their sampling distribution can be thought of as a statistical error on the limit. We thus introduce the concept of statistical errors of confidence limits and argue that not only should limits be calculated but also their errors in order to represent the results of the analysis to the fullest. We show that comparison of two different limits from two different experiments becomes easier when their errors are also quoted. Use of errors of confidence limits will lead to abatement of the debate on which method is best suited to calculate confidence limits.

physics.data-an↗
arXiv2001

The Program in Muon and Neutrino Physics: Super Beams, Cold Muon Beams, Neutrino Factory and the Muon Collider

We outline in detail a staging scenario for realizing the Neutrino Factory and the Muon Collider. As a first stage we envisage building an intense proton source that can be used to perform high intensity conventional neutrino beam experiments ("Superbeams"). While this is in progress, we perform R&D in collecting, cooling and accelerating muons which leads to the next two stages of "Cold Muon Beams" and the Neutrino Factory. Further progress in Muon Cooling especially in the area of emittance exchange will lead us to the Muon Collider. A staged scenario such as this opens up new physics avenues at each step and will provide a long range base program for particle physics.

hep-ex↗
arXiv1998

Calibrating the energy of a 50 X 50 GeV muon collider using spin precession

The neutral Higgs boson is expected to have a mass in the region 90-150 GeV in various schemes within the Minimal Supersymmetric extension to the Standard Model. A first generation Muon Collider is uniquely suited to investigate the mass, width and decay modes of the Higgs boson, since the coupling of the Higgs to muons is expected to be strong enough for it to be produced in the s channel mode in the muon collider. Due to the narrow width of the Higgs, it is necessary to measure and control the energy of the individual muon bunches to a precision of a few parts in a million. We investigate the feasibility of determining the energy scale of a muon collider ring with circulating muon beams of 50 GeV energy by measuring the turn by turn variation of the energy deposited by electrons produced by the decay of the muons. This variation is caused by the existence of an average initial polarization of the muon beam and a non-zero value of g-2 for the muon. We demonstrate that it is feasible to determine the energy scale of the machine with this method to a few parts per million using data collected during 1000 turns.

hep-ex↗
arXiv1997

Top quark mass measurements from the Tevatron

We review the measurements of the top quark mass by the CDF and D-Zero collaborations using Run I data in excess of 100 inverse picobarns. The D-Zero collaboration has recently updated its measurement of the top quark mass in the lepton + jets channel. The world average of the top quark mass from the CDF and D-Zero measurements in the lepton + jets channel now stands at 175.6 +/- 5.5 GeV/c**2.

hep-ex↗
arXiv1996

On Measuring the top quark mass using the dilepton decay modes

We demonstrate a new likelihood method for extracting the top quark mass from events of the type ttbar-->bW(l+nu)bW(l+nu) This method estimates the top quark mass correctly from an ensemble of dilepton events. The method proposed by Dalitz and Goldstein [1] is shown to result in a systematic underestimation of the top quark mass. Effects due to the spin correlations between the top and anti-top quarks are shown to be unimportant in estimating the mass of the top quark.

hep-ex↗
arXiv1994

Search for top in D-Zero using the electron + jets channel with soft muon tagging

We present preliminary results for the search for the top quark in D-Zero in the electron + jets channel where one of the b quark jets is tagged by means of a soft muon, using 13.5 pb-1 of data. Standard model decay modes for the top quark are assumed. We present the resulting top cross section and error as a function of top mass using this channel combined with the dilepton channel and the untagged lepton + jets channel . At present, no significant signal for top quark production can be established.

hep-ex↗