In this paper, we report on the design and operation of the LongBo time projection chamber in the Liquid Argon Purity Demonstrator cryostat. This chamber features a 2 m long drift distance. We measure the electron drift lifetime in the liquid argon u
sing cosmic ray muons and the lifetime is at least 14 ms at 95% confidence level. LongBo is equipped with preamplifiers mounted on the detector in the liquid argon. Of the 144 channels, 128 channels were readout by preamplifiers made with discrete circuitry and 16 channels were readout by ASIC preamplifiers. For the discrete channels, we measure a signal-to-noise (S/N) ratio of 30 at a drift field of 350 V/cm. The measured S/N ratio for the ASIC channels was 1.4 times larger than that measured for the discrete channels.
The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its ope
rations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.
From April to July 2013 the Snowmass Young Physicists (SYP) administered an online survey collecting the opinions and concerns of the High Energy Physics (HEP) community. The aim of this survey is to provide input into the long term planning meeting
known as the Community Summer Study (CSS), or Snowmass on the Mississippi. In total, 1112 respondents took part in the survey including 74 people who had received their training within HEP and have since left for non-academic jobs. This paper presents a summary of the survey results including demographic, career outlook, planned experiments and non-academic career path information collected.
