TBD + update on FRATs WG activities

Sander ter Veen
LOFAR Transients Key Project Meeting, Meudon, December 2011

Transcript

1. Progress
on
the
TBB
front:
 FRATS
and
Cosmic
Rays
 Sander
ter
Veen
 For
the
FRATS
working
group
and
the
 Cosmic
Ray
KSP

2. Transient
Buffer
Board
(TBB)
 Store
the
raw
data
of
each
dipole/1le
signal
in
a
RAM
ring
buffer

3. Taking
TBB
data
 Step
1:
 Step
2:
 Select
dipoles/staEons
 Select
5
μs
–


>1.3s
of
data

4. Turn
the
LOFAR
telescope
….

5. into
the
Virtual
LOFAR
telescope

6. High
Eme
resoluEon
(5ns)
 Large
bandwidth
(100
MHz)
 Lightning
flash
recorded
with
TBBs

7. All/large
sky
coverage
 Lightning
direc1on
finding
 LBA
all‐sky
image
with
1
sta1on

8. Near‐field
imaging
 Cosmic
Rays
 Pulsed
RFI

9. Parallel
system
 Imaging
+
Beamformed
 
 
 And
TBB
Cosmic
Rays!
 Credit:
George
Heald
and
LOFAR
Pulsar
Working
Group

10. Limited
Eme
 •  1.3
s
at
full
resoluEon
 •  More
Eme
by:
 – Less
bandwidth
 – 25s
@
5
MHz

 – Less
elements
 – More
memory
(upgrade
 to
5.2
s?)
 – 100s
@
5
MHz

11. Obtaining
TBB
data
 •  Current
framework:
Python
scripts
 – Trigger
handling
program
listens
for
triggers
(UDP
 packages)
 – If
a
trigger
is
received
check
if
dumping
is
allowed:
 •  Is
there
an
observaEon
running?
 •  Does
the
current
project
allow
dumping?
 •  Does
the
current
observaEon
allow
dumping?
 •  Is
dumping
allowed
on
all
observaEons
at
this
Eme?
 – Is
the
current
observaEon
excluded?
 •  Wanted:
key
that
tells
if
dumping
is
allowed
 – Execute
ssh
commands
at
the
staEon
to
tell
them
to
 dump
data


12. Official
TBB
Trigger
handling
 framework
 •  Triggerbox
(astronomer
program)
sends
 requests
(STOP,
DUMP,
RESTART)
 •  Requests
are
handled
by
central
system
(MAC)
 •  Central
system
checks
if
requests
can
be
 complied
to
 •  Central
system
asks
the
staEons
to
send
TBB
 data.
 •  Coming
soon…

13. TBB
data
writer
 •  A
new
data
writer
is
started
on
each
storage
 node
at
every
new
observaEon
 •  Part
of
the
metadata
is
added
to
the
previous
 observaEon
by
a
separate
program
 •  ASTRON
is
working
on
a
new
official
 supported
data
writer
including
metadata

 •  Similar
to
beam‐formed
HDF5
data
writer.
 •  New
data
writer
should
support
subband
data


14. Science
cases
 •  Fast
Radio
Transients
(FRATs)
 •  Very
High
Energy
Cosmic
Rays
(VHECR)
 •  Ultra
High
Energy
Cosmic
Rays
(NuMoon)

15. Possible
FRATs
Sources
 Millisecond
pulses
from:
 Pulsars/
RRATs
 (exo)
planets
 Flare
stars

16. Other
sparkers?
 Lorimer
et
al.
2007
 Keane
et
al.
2011

17. DetecEon
 •  Rare
events
 – Cover
large
area:
 • Incoherent
beam
 – Cover
long
duraEon:
 • Parallel
observaEons
 •  Dispersed
events:
 – MulEple
DM
trials
 •  Source
idenEficaEon:
 – Use
Transient
Buffer
Boards

18. FRATS
ObservaEon
Diagram
 Transient
Buffer
 Board
 Data
storage
 LOFAR
dipoles
 Trigger
 algorithm
 Dump
 request
 handler
 “Transient
detected”
 ObservaEon
 parameters
 BlueGene/P
 UV
Data
 BF
Data
 BF
Data
 TBB
Data


19. FRATS
 Real‐Eme
detecEon.
 Dedispersion
in
mulEple
frequency
bands
 Coincidence
requirement
between
the
bands
 Image
from
TBB
data
 Used
to
idenEfy
source

20. MSSS
+
FRATS
 •  Piggy‐back
on
MSSS
observaEons
 •  Add
incoherent
stokes
to
MSSS
observaEon
 •  Send
incoherent
stokes
to
separate
node
 •  Test
observaEons
showed
no
severe
data
loss
 on
imaging
data
 •  Test
run
last
weekend
(9‐11
december)
 – No
imaging
dataloss
in
all
but
1
(Cal.)
observaEon
 •  Incoherent
stokes
can
be
added

21. Current
Trigger
algorithm
issues
 •  In
progress:
Allow
for
non‐conEnuous
 frequency
axis
(MSSS)
 •  To
Do:
Smarter
RFI
checks
 – MulE‐beam
anE‐coincidence
 – DM=0
veto
with
last
N
samples
 – Pelican
rouEnes?
 •  To
Do:
Check
if
pulse
is
likely
from
a
known
 pulsar
(k3match)

22. To
Do:
TBB
data
reducEon
 •  TBB
data
volume
is
very
large
~
2
TB
 •  Data
volume
can
be
reduced
in
two
ways:
 • “staEon
beamforming”
 – Some
dipoles
to
form
a
staEon
beams
 
 – Factor
48
reducEon
 – But:
Lose
sensiEvity
outside
primary
beam
(RFI
in
sidelobes)
 • Coherent
dedispersion
 – Only
keep
a
fracEon
of
the
Emeseries
 – Factor
10‐100
 – But:
Unable
to
analyse
for
other
DMs

23. Cosmic
Rays
 Very
High
Energy
Cosmic
Rays

24. Why
study
Cosmic
Rays?
 •  Most
energeEc
parEcles
 •  Origin:
AGN
?
 •  To
determine
 – Chemical
composiEon
 – DirecEon
 – Energy
 •  Radio
emission
 – complementary
probe
 – 100%
duty
cycle

25. Radia1on
mechanisms
 •  Two
main
coherent
 emission
mechanisms:
 •  Charge
excess
 (Askaryan,
NuMoon
in
 air)
 •  GeomagneEc
effect

26. Why
CR
+
LOFAR
 •  Dense
instrumentaEon
(polarizaEon!)
 •  Probe
electromagneEc
field
at
many
points
 •  Pin
down
emission
processes
 •  Derive
the
properEes
of
air
showers
through
 radio
emission

 •  Measure
spectrum
and
composiEon
of
CR
 from
1017
‐1019
eV
(transiEon
GalacEc
to
 extragalacEc
origin)

27. Cosmic
Ray
Detec1on
 •  Two
methods:
 – Radio
self‐trigger
 • Any
LOFAR
staEon
(large
area)
 • But
also
RFI
triggers
 – LORA
triggered
 • No
false
triggers
 • Small
area
(only
CRs
near
Superterp)
 • Train
radio‐only
trigger
 •  Obtain
1‐5
ms
of
Transient
Buffer
Board
data

28. Royal
Fes1ve
Intermezzo
(RFI)

29. Effec1ve
RFI
excision

30. There
is
another
way:
 
 •  LOFAR
Radboud
air
shower
Array
(LORA)
 •  ScinEllator
array
on
superterp
detects
 electrons
and
muons.
 •  Coincidence
between
the
scinEllators
are
 cosmic
rays
 •  Trigger
TBBs
from
LORA

31. ObservaEon
Diagram
 Transient
Buffer
 Board
 Data
storage
 LOFAR
dipoles
 Dump
 request
 handler
 ObservaEon
 parameters
 BlueGene/P
 UV
Data
 BF
Data
 TBB
Data

 LORA
 ParEcle
 detector
 “Cosmic
Ray

 Detected”

32. Cosmic
Ray
Foot(finger)
Print

33. The
Virtual
LOFAR
telescope:
 TBB
data
+
pycrtools
(LUS)

34. Analysis
pipeline

35. Calibra1on

36. Peak
IdenEficaEon

37. Find
delays
between
dipoles

38. DirecEon
esEmaEon

39. Delay
stability

40. Beamforming

41. Lateral
DistribuEon
FuncEon

42. Theory
matches
signal?

43. Where
is
the
shower
core?

44. Where
is
the
shower
core?
 LDF,
LORA
esEmated
core

45. Where
is
the
shower
core?
 LDF,
Core
by
LOFAR
Barycenter

46. Where
is
the
shower
core?
 LDF,
LOFAR
ConEnuity
requirement

47. NuMoon
 •  CR
and
neutrino
>
10^21
eV
 •  Large
surface:
Moon
 •  Nanosecond
pulses
 •  Skip
2nd
PPF
Works
 •  Invert
staEon
PPF
 •  Correct
for
misalignment
from
clocks
 •  Noise
analysis
on
5
min
data
chunks

48. Conclusion
 •  TBBs
are
a
very
usefull
addiEon
to
the
system
 •  First
tests
FRATs
+
MSSS
succesful
 •  LOFAR
is
a
major
facility
for
radio
detecEon
of
 cosmic
rays
 •  Cosmic
Ray
observaEons
and
analysis
(almost)
 automated
 – SEll
manually
set
permissions
 – Manually
start
trigger
system
and
datawriters
on
 CEP
once.