Status of UA9

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Status of UA9
Walter Scandale CERN For the UA9 collaboration
(CERN, INFN, IHEP, PNPI JINR, SLAC, LBNL,
FNAL) LARP-CM13 5 November 2009
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Breaking new
Yesterday, in the last MD of 2009 we found that

• The leakage of the crystal assisted collimation
  in the SPS has been measured by a scan of the
  TIDP collimator in sextant 1
• Its rate was hardly measurable
• The crystal collimation efficiency was compatible
  with 100
• The diffractive event rate was negligible
• The fraction of particles in the clearance area
  between the extracted and the circulating beam
  was a few

The UA9 Collaboration is now ready to endorse the
extension of the study to LHC as soon as possible
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Outlook

• The UA9 layout
• First results
• Outlook for future

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UA9 layout
tank
IHEP tank
RP2
RP1
TAL (tungsten) 600x30x30 mm3
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UA9 layout
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UA9 layout
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UA9 layout
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UA9 layout
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UA9 layout
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The SPS beam

• Initial beam intensity single bunch of a few 109
  up to a few 1012.
• Initial beam lifetime larger than 80 h,
  determined by the SPS vacuum.
• Lifetime with the crystal at 6s 10 h (down to
  15 with the shaker on)
• Halo flux in the crystal a few 10 to a few 103
  particles per SPS turn

Nominal beam parameters
First hit footprint of the halo into the crystal
for a lifetime of the of 10 h.
RF Voltage MV 1.5
Momentum P GeV/c 120
Tune Qx 26.13
Tune Qy 26.18
Tune Qs 0.004
normalized emittance (at 1 ?) mm mrad 1.5
transverse radius (RMS) mm 1
momentum spread (RMS) ?p/p 4?10-4
Longitudinal emittance eV-s 0.4
Impact paramenter up to 0.1 mm impact angle 10
µrad
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Deflected beam
QF518
QF520
QD519
Particle trajectory with a150 µrad
taratin
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Expected efficiency for a150 ?rad
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News from UA9

• Crystal collimation effective during the SPS test
  runs
• The crystal collimation is based on channeling
  process.
• The deflected beam profile seen with a medipix
  detector.
• Background seen by Beam Loss Monitors,
  scintillator, Cerencov and GEM counters,
• Optimal crystal alignment easily detected and
  achieved
• Loss profile in the close-to-collimation area as
  expected from simulations
• BLM not sensitivity enough to inspect the
  background leakage along the ring
• Roman pot 2 and IHEP goniometer still missing
  (final assembly and tests in progress at CERN)
• Strategic issues
• Single particle tracking no longer of interest
  (too complex runs)
• Rate of diffractive and nuclear background larger
  in reflection that channeling mode

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A typical angular scan of the crystal 1
Amorphous orientation
Amorphous orientation
Reflection range
?
Channeling angle
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Extracted beam profiles with medipix
Crystal 1
The skew inclination of the extracted beam is due
to the combined effect of the strip crystal
residual torsion and to its quasi-axial
orientation that inducing channeling by the skew
crystal planes.
Crystal 2
An example of medipix detector
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Counting during a typical angular scan of crystal
1
Channeling from 7 planar configurations
The crystal is oriented in quasi-axial direction
Each of the three peaks corresponds to the the
channeling by a distinct skew plane
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A typical scan of the extracted by with the LHC
collimator
Preliminary estimate of the channeling efficiency
is 62 , to be compared with 92 predicted.
Intermediate gap in between the circulating and
the extracted beam seems to be populated with 23
of protons, to be compared with 1.3 expected.
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First attempt to estimate the crystal collimation
efficiency
Flux touching the crystal deduced from the beam
lifetime (5.81 107 particles in 85 s)
Flux touching the collimator (TAL)
(3.610.31) 107 particles
Analysis still on-going
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First attempt to estimate the nuclear rate in
channeling mode in H8
Background subtracted
Background non subtracted
Nuclear interaction probability with the crystal
in amorphous orientation
non-deflected beam fraction
Nuclear interaction probability with the crystal
in amorphous orientation
Nuclear rate in channeling orientation
Computed nuclear rate due to the non deflected
beam fraction
Nuclear interaction probability with the crystal
in channeling orientation
Background fraction
Analysis still on-going
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Future plans

• New station in the dispersive area after the
  crystal-collimation set
• stopper
• Cherencov in vacuum
• Roman pot with medipix
• The aim is to detect the leakage of the system
  and the diffractive events
• Two crystals in the LHC