118 research outputs found
Remember the Holocaust and the Killing Fields: A comparative Study
Why is the Holocaust almost universally remembered as the most horrific event in the modern age while the Cambodian genocide is hardly remembered both in and outside of Cambodia? Do the two events share similar aspects despite their differences, and what implication does that have on a wider understanding of both genocides? This thesis explores these questions by examining how the Holocaust and Cambodian genocide (killing fields) have been remembered over time. Examining both shows the respective roads of memorialization that each have taken and reveals where the two catastrophes share major aspects: notably, the tactics used by the perpetrators, the world’s failure to act, and the initial forced memorialization by third parties followed by a period of silence in the perpetrators and victims. This analysis focuses on three groups: the victims, the perpetrators, and third party countries – mainly America and Vietnam. The first two chapters focus on each genocide respectively by outlining how they have been remembered and what factors shaped, influenced, and hindered the process of memorialization. The third chapter compares and contrasts the two genocides, focusing on major similarities and differences between the two starkly different events. Examining the first four decades of Holocaust remembrance shows how its memorialization has become established. Focusing mostly on Jewish and German commemoration and how third party memorialization has affected this remembrance can reveal this process of establishment. Doing this reveals a deep struggle of Holocaust memory and an initial ignorance of world powers in recognizing the Jewish calamity within the context of the Second World War. Today, this can come as a surprise because the Holocaust is widely remembered and adapted into the narratives of many countries. Without studying the historiography of the Holocaust, one might assume that it was always openly and globally commemorated. However, this was not the case before the Israeli trial of Adolf Eichmann in 1961. It took Israel – the new Jewish state – to adapt the catastrophe into a suitable narrative, before the Holocaust became a publicly discussed topic anywhere else. This is the key reason why the Holocaust has been able to enter the realm of public commemoration while the Cambodian genocide has not – Cambodians do not have a separate state unlike world Jewry, which has Israel. Even so, the past struggles persist in Israeli and German narratives. Israel overemphasizes heroism in order to identify with the Holocaust; Germany has become torn between accepting past guilt and building a nation with a new image. Both of these elements have shaped how the Holocaust has been commemorated publicly in speeches, holidays, monuments, and museums. On the other hand, scholars interpret the Cambodian genocide differently amongst themselves. Some do not even consider the killing fields to be genocide while others label it another holocaust. It all depends on whether the focus is put on the numbers of those who were killed or on the actual experiences of the victims. Either way, even Cambodians struggle to remember their past. There are two significant causes for this. First, conflicting messages of peace and justice have prevented many Cambodians from knowing how to deal with their past – a struggle similar to the one Germany has experienced. Additionally, while the Holocaust ended for Jews after liberation, the Khmer Rouge continued to be a real threat to Cambodians for another 19 years. The effects of this can be seen in the topic’s absence in schools and its constrained public commemoration within the Tuol Sleng museum and Choeung Ek Genocidal Center. This struggle has only recently seen some improvements with the beginning of an international tribunal that is bringing a sense of justice to Cambodians, while also promoting education and public discussion about the past
A Search for Periodicities in the 8B Solar Neutrino Flux Measured by the Sudbury Neutrino Observatory
A search has been made for sinusoidal periodic variations in the 8B solar neutrino flux using data collected by the Sudbury Neutrino Observatory over a 4-year time interval. The variation at a period of one year is consistent with modulation of the 8B neutrino flux by the Earth’s orbital eccentricity. No significant sinusoidal periodicities are found with periods between 1 day and 10 years with either an unbinned maximum likelihood analysis or a Lomb-Scargle periodogram analysis. The data are inconsistent with the hypothesis that the results of the recent analysis by Sturrock et al., based on elastic scattering events in Super-Kamiokande, can be attributed to a 7% sinusoidal modulation of the total 8B neutrino flux
Data-driven Modeling of Electron Recoil Nucleation in PICO C3F8 Bubble Chambers
The primary advantage of moderately superheated bubble chamber detectors is their simultaneous sensitivity to nuclear recoils from weakly interacting massive particle (WIMP) dark matter and insensitivity to electron recoil backgrounds. A comprehensive analysis of PICO gamma calibration data demonstrates for the first time that electron recoils in C3F8 scale in accordance with a new nucleation mechanism, rather than one driven by a hot spike as previously supposed. Using this semiempirical model, bubble chamber nucleation thresholds may be tuned to be sensitive to lower energy nuclear recoils while maintaining excellent electron recoil rejection. The PICO-40L detector will exploit this model to achieve thermodynamic thresholds as low as 2.8 keV while being dominated by single-scatter events from coherent elastic neutrino-nucleus scattering of solar neutrinos. In one year of operation, PICO-40L can improve existing leading limits from PICO on spin-dependent WIMP-proton coupling by nearly an order of magnitude for WIMP masses greater than 3 GeV c-2 and will have the ability to surpass all existing non-xenon bounds on spin-independent WIMP-nucleon coupling for WIMP masses from 3 to 40 GeV c-
Measurement of the Cosmic Ray and Neutrino-Induced Muon Flux at the Sudbury Neutrino Observatory
Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between -1 ≤ cos Θ zenith ≤ 0:4 in a total exposure of 2.30 x 1014 cm^2 s. The measured flux normalization is 1.22±0.09 times the Bartol three-dimensional flux prediction. This is the fi rst measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO
with zenith angle cos Θ zenith > 0:4 is measured to be (3.31±0.01 (stat:) 0:09 (sys:)) x 10^-10 μ/s/cm^2
Measurement of Neutron Production in Atmospheric Neutrino Interactions at the Sudbury Neutrino Observatory
Neutron production in giga electron volt–scale neutrino interactions is a poorly studied process. We have measured the neutron multiplicities in atmospheric neutrino interactions in the Sudbury Neutrino Observatory experiment and compared them to the prediction of a Monte Carlo simulation using genie and a minimally modified version of geant4. We analyzed 837 days of exposure corresponding to Phase I, using pure heavy water, and Phase II, using a mixture of Cl in heavy water. Neutrons produced in atmospheric neutrino interactions were identified with an efficiency of 15.3% and 44.3%, for Phases I and II respectively. The neutron production is measured as a function of the visible energy of the neutrino interaction and, for charged current quasielastic interaction candidates, also as a function of the neutrino energy. This study is also performed by classifying the complete sample into two pairs of event categories: charged current quasielastic and non charged current quasielastic, and νμ and νe. Results show good overall agreement between data and Monte Carlo for both phases, with some small tension with a statistical significance below 2σ for some intermediate energies
Dark Matter Search Results from the Complete Exposure of the PICO-60 C3F8 Bubble Chamber
Final results are reported from operation of the PICO-60 C3F8 dark matter detector, a bubble chamber filled with 52 kg of C3F8 located in the SNOLAB underground laboratory. The chamber was operated at thermodynamic thresholds as low as 1.2 keV without loss of stability. A new blind 1404-kg-day exposure at 2.45 keV threshold was acquired with approximately the same expected total background rate as the previous 1167-kg-day exposure at 3.3 keV. This increased exposure is enabled in part by a new optical tracking analysis to better identify events near detector walls, permitting a larger fiducial volume. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.2×10-41 cm2 for a 25 GeV WIMP, improving on previous PICO results for 3-5 GeV WIMPs by an order of magnitude
Constraints on Neutrino Lifetime from the Sudbury Neutrino Observatory
The long baseline between Earth and the Sun makes solar neutrinos an excellent test beam for exploring possible neutrino decay. The signature of such decay would be an energy-dependent distortion of the traditional survival probability which can be fit for using well-developed and high-precision analysis methods. Here a model including neutrino decay is fit to all three phases of 8B solar neutrino data taken by the Sudbury Neutrino Observatory (SNO). This fit constrains the lifetime of neutrino mass state ν2 to be >8.08×10−5  s/eV at 90% confidence. An analysis combining this SNO result with those from other solar neutrino experiments results in a combined limit for the lifetime of mass state ν2 of >1.92×10−3  s/eV at 90% confidence
Electron Antineutrino Search at the Sudbury Neutrino Observatory
Upper limits on the v¯e flux at the Sudbury Neutrino Observatory have been set based on the v¯e charged-current reaction on deuterium. The reaction produces a positron and two neutrons in coincidence. This distinctive signature allows a search with very low background for v¯e’s from the
Sun and other potential sources. Both differential and integral limits on the v¯e flux have been placed in the energy range from 4 – 14.8 MeV. For an energy-independent ve -> v¯e conversion mechanism, the integral limit on the flux of solar v¯e’s in the energy range from 4 – 14.8 MeV is found to be Φv¯e ≤ 3.4 × 104cm−2s−1 (90% C.L.), which corresponds to 0.81% of the standard
solar model 8B e flux of 5.05 × 106cm−2s−1, and is consistent with the more sensitive limit from KamLAND in the 8.3 – 14.8 MeV range of 3.7×102cm−2s−1 (90% C.L.). In the energy range from 4 – 8 MeV, a search for v¯e’s is conducted using coincidences in which only the two neutrons are
detected. Assuming a v¯e spectrum for the neutron induced fission of naturally occurring elements, a flux limit of Φv¯e 2.0 × 106cm−2s−1 (90% C.L.) is obtained
Improved Spin Dependent Limits from the PICASSO Dark Matter Search Experiment
The PICASSO experiment reports an improved limit for the existence of
cold dark matter WIMPs interacting via spin-dependent interactions with nuclei. The experiment is installed in the Sudbury Neutrino Observatory at a depth of 2070 m. With superheated C4F10 droplets as the active material, and an exposure of 1.98±0.19 kgd, no evidence for a WIMP signal was found. For a WIMP mass of 29 GeV/c2, limits on the spin-dependent cross section on protons of σp = 1.31 pb and on neutrons of σn = 21.5 pb have been obtained at 90% C.L. In both cases, some new parameter space in the region of WIMP masses below 20 GeV/c2 has now been ruled out. The results of these measurements are also presented in terms of limits on the effective WIMP-proton and neutron coupling strengths ap and an
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