Transcript cosmic ray astronomy  air showers for cyclists  particle physics as sytematics  progress through instrumentation (LHC)  GZK neutrinos versus >1020 eV.

cosmic ray astronomy
 air showers for cyclists
 particle physics as sytematics
 progress through instrumentation (LHC)
 GZK neutrinos versus >1020 eV protons (?)
air showers
• the atmosphere is a detector with a total depth
of 25 radiation length (le) and 10 interaction length (line).
• an electromagnetic shower penetrates N radiation
lengths until the particle energy is reduced to the
critical energy of Ec~85 MeV where pair production
stops and the shower is absorbed in the atmosphere.
It is observed by the detection of electrons, positrons and
(mostly) photons.
• a hadronic showers travels N’ interaction lengths producing
pions down to an energy ep where the pion interaction length
is shorter than its decay length. At that point muon production
stops.
electromagnetic showers
cross sections for g + air  e++e- and e + air  g+e
are approximately equal
electromagnetic showers
num berof particlesn after N steps; depth X  N le
n X   2  2
N
X
Ei
Ei
and E  X   N  X
2
le
2
le
after com pletedevelopm ent N max  le X max
E  X max   Ec 
Ei
X max
2
X max
 nmax  2
le
therefore
X max
Ei
 le ln
Ec
and nmax
Ei

Ec
N max
2
le
Ei

Ec
hadronic showers
le
g  e  e
line p  n p 0  p   p   with p 0  g  g  em shower
p ch      m uons
  2 N 
Ehad
and Eem  1     Ei
  3  
electrom agnetic shower dictates total depth
N
2
   Ei
3
 Ei 

X  line  X  line  ln
 n Ec 
hadronicshower : N line from Ei  e p  150GeV
em
max
Ei
ep  N
n
e
max
 n  nch
N
 Ei
 
 ep




ln nch
with  
 0.82  0.95
ln n
showers: nuclei
E
m ass A with energyE  A showers with energy
A
E p Ei
Ei
A
A
N max  A

 N max and X max 
X max
Ec Ec
A

 Ei / A 
  A1 n
n  A 
 ep 
A
cosmic ray astronomy
 air showers for cyclists
 particle physics as systematics
 progress through instrumentation (LHC)
 GZK neutrinos versus >1020 eV protons (?)
confirmed by
Telescope Array
GZK absorption
feature appears
at the expected
energy
Auger : the sources revealed ?
correlation of arrival directions with active galaxies
proton astronomy ?
pointing of cosmic rays :
d
dB


Rgyro
E
 d 
B


  9

  10 Mpc   10 Gauss 

E
1
20
3  10 eV
Cen A at only < 4 Mpc but …
energetics sufficient?
spectral energy distribution of Cen A (variability!)
Magic
M87!
• are the highest cosmic rays heavy nuclei ?
• pointing ?
HiRes disagrees on everything except GZK
• isotropic arrival directions
• protons (shower max and fluctuations)
•
•
•
•
is reason data or simulation?
how can fluctuations disagree?
direct “confrontation” highly desirable
also, TA
cosmic ray astronomy
 air showers for cyclists
 particle physics as sytematics
 progress through instrumentation (LHC)
 GZK neutrinos versus >1020 eV protons (?)
muon problem
can theorists change protons to into iron?
The extrapolation of the cross section, multiplicity of secondaries
and
inelasticity not controlled.
bistatic radar:
forward scattering off ionization cloud
produced by air shower
cosmic ray astronomy
 air showers for cyclists
 particle physics as sytematics
 progress through instrumentation (LHC)
 GZK neutrinos versus >1020 eV protons (?)
cosmic rays interact with the
microwave background
p  g  n  p and p  p

0
p   
cosmic rays disappear, neutrinos appear
p      {e      e }   
E   2  10 TeV
6
~ 1 event per kilometer squared per year
neutrinos
from
GZK
interactions

also
photons that
cascade on
background
light
galactic
extragalactic

limits GZK
flux
electromagnetic cascade peaks at 100 GeV  GZK < Fermi flux
radio emission from GZK neutrinoinduced electromagnetic cascades
• electromagnetic cascades: electron-positron pairs and
(mostly) gammas  electrically neutral, no radio emission.
• but, Compton scattering of photons on atomic electrons creates
negative charge excess of ~ 20%
• negative charge radiates coherently at MHz ~ GHz 
Power = Energy 2
• GZK neutrinos point at the sources
• they are complementary to 1020 eV events
Livingston plot :
energy versus year
• ~ 1 event per year
in IceCube
• radio/acoustic
domain
• priority: determine
the event rate!
Asakaryan array
 Arianna array
SLAC T486 (July 06): Askaryan on ice
10 ns
• Opportunity to test the effect in a
medium relevant to several current
and future experiments:
ANITA, RICE, etc.
•12-tons of ice + ANITA +
End Station A + SLAC beam = Ideal ANITA
calibration + comprehensive
validation of Askaryan
RICE
Radio Detection in South Pole Ice
Neutrino enters ice
Neutrino interacts
Antenna
& Cable
• installed 15 antennas
few hundred m depth with
AMANDA strings.
• tests and data since 1996.
• most events due to local
radio noise, few candidates.
• continuing to take data.
• Askaryan Radio Array
near IceCube : first
deployments December 2010
Cube is .6 km on side
Two cones show 3 dB
signal strength
in-ice view of radio detection with antennas
 200m deep for ARA
 at the surface for ARIANNA
ARIANNA concept
100 x 100 station array
Ross Ice Shelf, Antarctica
Antarctic Impulsive Transient Antenna Experiment
2 candidate events
Solar
panels
Antenna array
Overall height ~8m
ANITA
Gondola &
Payload
RF
Cherenkov
air
searching for GZK
neutrinos with radio
detection in Antarctic ice
solid
neutrino
Cascade: ~10m length
reflected and direct events


ignore
Direct
ice
Reflected
(much greater solid angle)
sensitivity to neutrino
cross section !