David P. McGinnis

The Sloan Digital Sky Survey - II:supernova survey: technical summary

The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5° wide centered on the celestial equator in the Southern Galactic Cap that has been imaged numerous times in earlier years, enabling construction of a deep reference image for the discovery of new objects. Supernova imaging observations are being acquired between September 1 and November 30 of 2005-7. During the first two seasons, each region was imaged on average every five nights. Spectroscopic follow-up observations to determine supernova type and redshift are carried out on a large number of telescopes. In its first two three-month seasons, the survey has discovered and measured light curves for 327 spectroscopically confirmed SNe Ia, 30 probable SNe Ia, 14 confirmed SNe Ib/c, 32 confirmed SNe II, plus a large number of photometrically identified SNe Ia, 94 of which have host-galaxy spectra taken so far. This paper provides an overview of the project and briefly describes the observations completed during the first two seasons of operation.

The Sloan Digital Sky Survey-II Photometry and Supernova IA Light Curves from the 2005 Data

We present ugriz light curves for 146 spectroscopically-confirmed or spectroscopically-probable Type Ia supernovae (SNe) from the 2005 season of the Sloan Digital Sky Survey-II Supernova (SN) survey. The light curves have been constructed using a photometric technique that we call scene modeling, which is described in detail here; the major feature is that SN brightnesses are extracted from a stack of images without spatial resampling or convolution of the image data. This procedure produces accurate photometry along with accurate estimates of the statistical uncertainty, and can be used to derive photometry taken with multiple telescopes. We discuss various tests of this technique that demonstrate its capabilities. We also describe the methodology used for the calibration of the photometry, and present calibrated magnitudes and fluxes for all of the spectroscopic SNe Ia from the 2005 season.

A Measurement of the Rate of Type Ia Supernovae at Redshift z ≈ 0.1 from the First Season of the SDSS-II Supernova Survey

We present a measurement of the rate of Type Ia supernovae (SNe Ia) from the first of three seasons of data from the SDSS-II Supernova Survey. For this measurement, we include 17 SNe Ia at redshift z ≤ 0.12. Assuming a flat cosmology with Ωm = 0.3 = 1 − ΩΛ, we find a volumetric SN Ia rate of [ 2.93+ 0.17−0.04(systematic)+ 0.90−0.71(statistical) ] × 10−5 SNe Mpc −3 h370 yr −1, at a volume-weighted mean redshift of 0.09. This result is consistent with previous measurements of the SN Ia rate in a similar redshift range. The systematic errors are well controlled, resulting in the most precise measurement of the SN Ia rate in this redshift range. We use a maximum likelihood method to fit SN rate models to the SDSS-II Supernova Survey data in combination with other rate measurements, thereby constraining models for the redshift evolution of the SN Ia rate. Fitting the combined data to a simple power-law evolution of the volumetric SN Ia rate, rV ∝ (1 + z)β, we obtain a value of β = 1.5 ± 0.6, i.e., the SN Ia rate is determined to be an increasing function of redshift at the ~2.5 σ level. Fitting the results to a model in which the volumetric SN rate is rV = Aρ(t) + B(t), where ρ (t) is the stellar mass density and (t) is the star formation rate, we find A = (2.8 ± 1.2) × 10−14 SNe M−1☉ yr −1, B = (9.3+ 3.4−3.1) × 10−4 SNe M−1☉.

First-year spectroscopy for the sloan digital sky survey - II. Supernova survey

This paper presents spectroscopy of supernovae (SNe) discovered in the first season of the Sloan Digital Sky Survey-II SN Survey. This program searches for and measures multi-band light curves of SNe in the redshift range z = 0.05-0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the SN population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our SN spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the SN and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host-galaxy contamination existing in the majority of our SN spectra.

Beam decelerations with variable momentum compaction in the Fermilab Antiproton Accumulator

Abstract For the study of charmonium resonances above and including the χ c 0 , Fermilab experiment E-835 required an intense and stochastically cooled antiproton beam with kinetic energies from 8 GeV (the injection energy of the Accumulator) down to 4 GeV . We developed a scheme in which the momentum compaction factor of the machine was changed as the antiprotons were decelerated, so that the energies of interest to the experiment were kept above transition. The scheme was used during the E-835 10-month run of the year 2000. Here we describe the design criteria, operational procedures and diagnostic tools we used to exploit the machine as an efficient antiproton decelerator. The machine performance during data taking is also discussed, in relation to the main experimental requirements.

Performance and Upgrades of the Fermilab Accumulator Stacktail Stochastic Cooling

We report on the performance and planned upgrades to the Fermilab Accumulator Stacktail Stochastic Cooling System. The current system has achieved a maximum flux of 16.5e10/hour, limited by the input flux of antiprotons. The upgrades are designed to handle flux in excess of 40e10/hour.

Performance of the upgraded Stacktail Momentum Cooling system in the Fermilab antiproton source

Major changes in the Stacktail Momentum Stochastic Cooling system have resulted in an improved stacking rate as well as the capability to stack larger quantities of antiprotons. Both these effects result in higher initial and integrated luminosity for colliding beam physics. An over view of the changes and actual system performance will be presented.<<ETX>>

An introduction to stochastic cooling

The basic concepts of stochastic cooling of proton beams are reviewed. Betatron oscillations are the prime topic of discussion. Experimental methods such as pickups and kickers are analyzed. (AIP)

A nondestructive fast beam profile monitor

Abstract A nondestructive beam profile monitor has been built and installed in the Fermilab booster synchrotron. The detector collects and amplifies the signal from the residual vacuum gas ions created by the passage of the beam. The new feature of this detector is the fast electronics used to amplify and record the signal. It is now possible to observe fast transverse beam dynamics on a timescale of one orbit. The design and performance of the profile monitor are described.

Debuncher cooling performance

We present measurements of the Fermilab Debuncher momentum and transverse cooling systems. These systems use liquid helium cooled waveguide pickups and slotted waveguide kickers covering the frequency range 4-8 GHz.