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Chooz (experiment) AI simulator
(@Chooz (experiment)_simulator)
Chooz (experiment)
Chooz (French pronunciation: [ʃo] ⓘ) was a short baseline neutrino oscillation experiment in Chooz, France. Its major result was setting limits on the neutrino oscillation parameters responsible for changing electron neutrinos into other neutrinos. Specifically, it found that sin2(2θ13) < 0.17 for large δm2 and δm2 > 8×10−4 eV2 for maximal mixing. The results were published in 1999.
The Double Chooz experiment continues to take data using the same lab space.
Chooz used neutrinos from two pressurized water reactors, which provided a >99.999% ν
e source. The average neutrino energy was approximately 3 MeV, and the detector was roughly 1000 m from the reactor. The intensity was measured using both the heat balance and neutron output of the reactor, and was known to be better than 2%. Detailed modeling of the reactor cores was used to predict both the intensity and energy spectrum of the neutrinos as a function of time. Neutrinos were observed via the inverse beta decay reaction (p + ν
e → n + e+
).
The Chooz detector was underground, with a 300- meter water equivalent overburden to reduce cosmic ray backgrounds. The detector itself was a cylinder 5.5 m in diameter and 5.5 m tall. The detector was composed of three regions. The innermost region (region I) contained 5 tons of scintillator doped with gadolinium in a Plexiglas container. The gadolinium quickly captured the neutrons produced in the inverse beta decay. The second region (region II) contained 17 tons of undoped scintillator to capture the electromagnetic energy from the inverse beta decay (≈99%) and the photons from the neutron capture in the Gd (>95%). The outer surface of region II contained 192 inward facing photomultiplier tubes (PMT) held in an opaque plastic structure.
The outermost region (region III) contained ninety tons of the same undoped scintillator as region II and vetoed cosmic ray events using 48 PMTs.
The Plexiglas layer between regions I and II was clear, to allow scintillation light from region I to be observed by the PMTs in region II. The inner surface of the region II container was painted black to avoid reflections, which would degrade position measurements. The outer surface of the region II container and the inner surface of the region III container were painted white to maximize the veto signals.
Chooz collected data for a total of 8210 hours: 3420 hours with neither reactor running, 3250 hours with one reactor running, and 1540 hours with both reactors running. A total of 2991 neutrino candidates were observed during this period, with 287 of the candidates occurring during the reactor off periods. The correlated background was 1.01 events per day, and the uncorrelated background was 0.42 events per day. The neutrino yield was also studied as a function of reactor power, fuel burnup, and for each reactor separately.
The energy spectrum of the positrons and the calculated direction of the incoming neutrino were also calculated. All distributions agreed with predictions.
Chooz (experiment)
Chooz (French pronunciation: [ʃo] ⓘ) was a short baseline neutrino oscillation experiment in Chooz, France. Its major result was setting limits on the neutrino oscillation parameters responsible for changing electron neutrinos into other neutrinos. Specifically, it found that sin2(2θ13) < 0.17 for large δm2 and δm2 > 8×10−4 eV2 for maximal mixing. The results were published in 1999.
The Double Chooz experiment continues to take data using the same lab space.
Chooz used neutrinos from two pressurized water reactors, which provided a >99.999% ν
e source. The average neutrino energy was approximately 3 MeV, and the detector was roughly 1000 m from the reactor. The intensity was measured using both the heat balance and neutron output of the reactor, and was known to be better than 2%. Detailed modeling of the reactor cores was used to predict both the intensity and energy spectrum of the neutrinos as a function of time. Neutrinos were observed via the inverse beta decay reaction (p + ν
e → n + e+
).
The Chooz detector was underground, with a 300- meter water equivalent overburden to reduce cosmic ray backgrounds. The detector itself was a cylinder 5.5 m in diameter and 5.5 m tall. The detector was composed of three regions. The innermost region (region I) contained 5 tons of scintillator doped with gadolinium in a Plexiglas container. The gadolinium quickly captured the neutrons produced in the inverse beta decay. The second region (region II) contained 17 tons of undoped scintillator to capture the electromagnetic energy from the inverse beta decay (≈99%) and the photons from the neutron capture in the Gd (>95%). The outer surface of region II contained 192 inward facing photomultiplier tubes (PMT) held in an opaque plastic structure.
The outermost region (region III) contained ninety tons of the same undoped scintillator as region II and vetoed cosmic ray events using 48 PMTs.
The Plexiglas layer between regions I and II was clear, to allow scintillation light from region I to be observed by the PMTs in region II. The inner surface of the region II container was painted black to avoid reflections, which would degrade position measurements. The outer surface of the region II container and the inner surface of the region III container were painted white to maximize the veto signals.
Chooz collected data for a total of 8210 hours: 3420 hours with neither reactor running, 3250 hours with one reactor running, and 1540 hours with both reactors running. A total of 2991 neutrino candidates were observed during this period, with 287 of the candidates occurring during the reactor off periods. The correlated background was 1.01 events per day, and the uncorrelated background was 0.42 events per day. The neutrino yield was also studied as a function of reactor power, fuel burnup, and for each reactor separately.
The energy spectrum of the positrons and the calculated direction of the incoming neutrino were also calculated. All distributions agreed with predictions.