Transcript Svoboda, PPTX, 14 MB

DUNE Supernova Capabilities
R.Svoboda
November 23, SLAC
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DUNE
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DUNE Far Detector Conceptual Design
Field
Cage
Membrane
cryostat
14.4 m
CPAs
12 m
CPAs
APAs
APAs
APAs
3.6m
Field
Cage
Steel Cryostat
Detector Parameters (One 10-kton Module)
58 m x 12 m x 14.4 m (~50 times larger than ICARUS)
Alternating Anode and Cathode Plane Assemblies resulting in four 3.6 m drift volumes
Modular design to facilitate underground transport and installation
Detector will fit in the cryostat planned
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Schedule
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Single Phase LAr TPC
Operating principles
ionizing events taking place in a
volume of LAr (where a uniform
electric field is applied) produce
electron-ion pairs
These charges drift along the field
lines. The motion of the much faster
electrons induces a current on the
anode. The electrons can drift several
metres if the LAr is highly purified
(electronegative impurities < 0.1 ppb
O2 equiv.)
F. Arneodo , ICARUS
F. Arneodo , ICARUS
Non-destructive multiple readout
Raw Data from a 10 m3 prototype
eIonizing track
Charge
Scintillation Light
2nd
Induction wire
grid (x view)
d
d
p
Charge
1st Induction
wire/screen grid
Signals induced
C
A
Time -drift
B Drift time
C
Collection wire
grid (y view)
A B
Drift time
400 ns sampling
Continuous
waveform
recording
F. Arneodo Imaging 2003
Liquid Argon TPC
Advantages
• tracks recorded at sub 1mm
level. Easy to distinguish
multiple and/or complex
events
• recoil hadrons visible even
below Cherenkov threshold
• Argon is a scintillator
• Argon is relatively cheap
(comparable to scintillator)
• Significant ne cross section
at low energy
Disadvantages
• Drift is slow compared to
Cherenkov or scintillation
(~2 ms for DUNE)
• Need scintillation light
collection for a "t0" and
hence position in volume
• Complex nucleus compared
to oxygen or carbon.
Complicated cross-sections.
• No free protons
• No neutron capture tagging
Resonant neutron capture cross section on argon has large dip in the 50 keV region
Slow energy loss due to heavy nucleus means neutrons can travel many 10's of
meters before capture. Likely leave sensitive volume and not be recorded.
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Steven Gardiner
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Chris Grant
We could measure this with a fairly
significant effort. Is it worth it?
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Also possible at NuMI
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Why Measure SN Bursts in DUNE?
And why is it important to know the absolute
cross-section, energy reconstruction ? Many reasons.
Here are a few examples in the literature
Neutrino cooling of the proto-neutron star is very sensitive
to sterile neutrinos, which not only alter the flavor content
of the neutrino flux, but also affect the efficiency (and hence
time scale) or cooling.
Example: see Irene Tamborra, Georg G. Raffelt, Lorenz H ̈udepohlb,
and Hans-Thomas Jankab "Impact of eV-mass sterile neutrinos on
neutrino-driven supernova outflows" JCAP (2012). Also arXiv:1110.2104v3
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0.5s
0.5 seconds after core bounce at r=1000km from the proto-neutron star.
Neutrinos experience a very significant MSW resonance, causing almost
complete conversion to sterile. Anti-neutrinos do not have an MSW resonance
in an adiabatic conversion region, so there is almost no conversion.
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2.9s
We would
not have
seen this
in SN1987A
since sterile
contribution is
in electron
neutrinos and
not anti-neutrinos
6.5s
2.9 and 6.5 seconds after core bounce at r=1000km from the proto-neutron
star. Color is same as for previous plot
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• Need to know absolute exclusive cross-sections
better than the current 30-40% level to look for
differences between WC, LS, LAr detectors
• Need to understand NC cross-section as a
possible second check on the total (integrated)
flux.
• ANY COOLING MECHANISM BEYOND "URCA"
WILL PRODUCE A SIMILAR EFFECT (axions, dark
matter, mirror matter, dark photons, etc.)
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Dark Photons
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Fig. 6. Parameter space in the dark photon (mγ′,ϵ)(mγ′,ϵ) plane excluded by the supernova (relevant) observations and the
experiments E137 [16] and E141 [17].
Demos Kazanas, Rabindra N. Mohapatra, Shmuel Nussinov, Vigdor L. Teplitz, Yongchao Zhang
Supernova bounds on the dark photon using its electromagnetic decay
Nuclear Physics B, Volume 890, 2015, 17–29
http://dx.doi.org/10.1016/j.nuclphysb.2014.11.009
With 1000's of events one can
dramatically reduce systematic
and statistical uncertainty. SN
could give a first hint of DM for
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this type of scenario.
Measurement of Time-Structure
Standing Accretion Shock Instability
(SASI) frequencies of
~80 Hz are predicted by some
models. These cause a variation
in the neutrino flux that may be
detectable.
If we can see these then it
means the neutrinos remained
coherent to 10 ms levels over
galactic distances. Affected by
absolute mass and energy.
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Variation in Luminosity is significant.
Possibly detectable.
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DUNE Design Questions
1. What features should DUNE be sensitive to in
both the neutronization and cooling phase?
Why are these features important
scientifically?
This will impact calibrations, energy resolution requirements,
timing capabilities, photon collection system, and so on
Not all aspects can be optimized to the maximum possible. This
would require too much time and money. We have to choose
were we put resources.
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Neutral Currents
2. Detection of the NC reaction on
argon may be possible to extract
from the detector with sufficient
energy resolution and with work
done beforehand to verity the
existence of a monoenergetic
gamma ray from the reaction.
How important is this? What
would be the scientific payoff?
How important is it to disentangle
the flavor components of the
signal?
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Looking for the unexpected
3. Are there other feature or possibilities in the SN burst that we
should be prepared to measure outside of the standard
understanding of the physics of stellar collapse?
4. Are there other feature or possibilities in the SN burst that we
should be prepared to measure that would be important to
particle physics, such as mass hierarchy, collective effects, sterile
neutrinos, or new interactions or particles? Are there robust
signatures for these?
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Diffuse SN Flux
5. In addition, measurement of Diffuse SN Background neutrinos
will be difficult in DUNE. Is there a reason why detection in
electron neutrinos would be especially compelling scientifically?
Argon is a relatively heavy nucleus compared to oxygen or carbon.
There is no neutron "double coincidence" flag
Spallation daughter background is expected to be significant, but is unmeasured
Controlling radon, U/Th and other contaminants in the construction and operation
would be expensive and time consuming. It could lead to $10M's and significant
delays in schedule.
We would do this is compelling. Is it?
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Design questions...
1. What timing is required to see such features? There is a big difference in cost
and R&D effort in going from 2 milliseconds absolute and relative timing to 100
microsconds resolution. What do we gain?
2. What energy resolution is required to see scientifically interesting features?
What would be the scientific loss if resolution were 30% versus 10% versus 3%?
Note that time, money, and engineering effort to achieve such precise energy
information is decidedly non-linear in the required precision.
3. We may not be able to take all events in a close SN. If the DAQ becomes
saturated, we may have to either stop data taking at some point or pre-scale
recording events. For example, we could record only 20% of all incoming data in
order to get an unbiased snapshot of the whole burst. What is the best strategy to
follow and why?
4. To what level must we be able to measure the absolute neutrino flux? In other
words, if the cross-section were only known to 50% versus 25% versus 5%, what
would we lose scientifically?
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Summary
• There are choices to be made in the design of
the DUNE detector. The time scale is relatively
short. In six months the design of the first
module will be frozen.
• The recommendations from this group will
have significant impact on the field for the
next twenty years or more.
• Thank you in advance! We look forward to
your report.
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