Particle Physics Booklet - Particle Data Group - Lawrence Berkeley ...

260 29. Detectors for non-accelerator physics
No detection of astrophysical neutrinos has been made yet. Two limits
from AMANDA to such E neutrino fluxes are shown: one is a diffuse
muon neutrino flux limit [48], the other is a limit based on all flavor
analysis of non-contained events in the PeV to EeV energy region [49]
Eν dNν/dEν [GeV cm−2 s−1 sr−1 2
]
10 −3
10 −4
10 −5
10 −6
10 −7
10 −8
10 −9
102 103 104 105 10−10 Atmospheric neutrino model
Gamma-ray bursts
Waxman-Bahcall bound
Cosmogenic neutrino flux
AMANDA-II unfolded ν μ
AMANDA II ν μ × 3
AMANDA II cascades prelim.
IceCube projected 1 year ν μ × 3
10
Eν [GeV]
6 107 108 109 10 10 1011 1012 Figure 29.3: Measured atmospheric neutrino fluxes above 100 GeV
are shown together with a few generic models for astrophysical
neutrinos and some limits. See full-color version on color pages at
end of book.
29.4. Large time-projection chambers for rare event
detection
Written August 2009 by M. Heffner (LLNL).
TPCs in non-accelerator particle physics experiments are principally
focused on rare event detection (e.g., neutrino and dark matter
experiments) and the physics of these experiments can place dramatically
different constraints on the TPC design (only extensions of the traditional
TPCs are discussed here). The drift gas or liquid is usually the target or
matter under observation and due to very low signal rates a TPC with
the largest possible active mass is desired. The large mass complicates
particle tracking of short and sometimes very low-energy particles. Other
special design issues include efficient light collection, background rejection,
internal triggering, and optimal energy resolution.
The liquid-phase TPC can have a high density at low pressure that
results in very good self-shielding and compact installation with lightweight
containment. The down sides are the need for cryogenics, slower charge
drift, tracks shorter than typical electron diffusion distances, lower-energy
resolution (e.g., xenon) and limited charge readout options. Slower charge
drift requires long electron lifetimes, placing strict limits on the oxygen
and other impurities with high electron affinity.
A high-pressure gas phase TPC has no cryogenics and density is easily
optimized for the signal, but a large heavy-pressure vessel is required.