Start of Beam Commissioning of
the Extra Low ENergy Antiproton
ring (ELENA)
C. Carli on behalf of the AD/ELENA team(s)
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ABP Information Meeting 20th April 2017
ELENA Overview and Layout
Start of ELENA Commissioning
Next Steps
Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017
ELENA Overview and Layout
Injection with magnetic
septum and kicker
High sensitivity
magnetic Pick-up
(Schottky diagnostics
for intensity, LLRF..)
Extraction towards
new experimental zone (fast deflector)
followed by el.-static transfer lines
Compensation
solenoids
for (not yet
Installed) cooler
Line
From AD
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Extraction towards
existing experiments
Scraper to measure
emittance
Wideband RF cavities
(very similar to new
PSB cavities)
Deceleration of antiprotons from 5.3 MeV to 100 keV to improve efficiency of experiments
Circumference 30.4 m (1/6 the size of the AD), magnetic ring and electrostatic extraction lines
Challenges related to low energy as field quality of magnets operated with very low fields
Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017
Start of ELENA Commissioning –
Ion Source
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Aim: progress as much as possible without taking
“expensive” antiprotons
Source available and tested well in advance
Source
Faraday cage
100 keV (post-acceleration), source a few meters
from Faraday cage with HV cables in between
 First tests with source mounted in Faraday cage
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Technical issues despite serious preparations
Isolation transformer(s) broke several times
=>Now running with fixed transformer at 85 keV
 No beam since last week due to vacuum issues
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Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017
Start of ELENA Commissioning –
Transfer line
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Source
Profile monitor prototype
issues to interpret signals
available since ~a month
Electro-static line from source to ring
Missing monitors (in-kind) make understanding
difficult
 Empirical adjustments allowed bringing the
beam to ring within few days, but led to
unexpected settings
 Excellent to see beam on TV station close
to ring
 Recent efforts to be invested to understand
did not (yet?) improve
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Signals from horizontal wires
TV station almost
only instrumentation
available
Start of ELENA Beam Comissioning
One of the first acquisitions
from November 2016
ABP Meeting, 20th April 2017
Start of ELENA Commissioning –
Ring
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Beam observed over several 10s of turns
(probably a few ms) in November ‘16
after less than 2 weeks
Position pick-up sum signals
50 ms/div
Beam lost quickly or just not visible
any more due to debunching?
 Commissioning of RF system as next
under preparation, when source broke
(insulation transformer)
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With 85 keV H- after commissioning of RF system
Beam shown to survive at least until start of ramp
 Only very basic RF functionalities, no phase loop
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50 ms/div
Tunes from injection oscillations using OASIS
1 ms/div
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Synchrotron oscillation, debunching …. Seen
with OASIS
Start of ELENA Beam Comissioning
About 150 ms after injection
~1.5 106 H- ???
ABP Meeting, 20th April 2017
ELENA Commissioning –
Next Steps
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Get ion source up and running again
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Briefly switch to protons for a test of the profile monitor, then probably 85 keV H- to resume
ring commissioning (stay at 85 keV even with new isolation transformer?)
Consolidate injection line and injection into ring
First: back to injection line setting from 5th and 6th April, when injection was good
 Further studies to understand and empirically improve line and injection
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Commissioning of instrumentation and
understanding machine at low energy
Orbit system – orbit correction and orbit
response studies
 “Tomoscope” – observe bunching
(& independent intensity estimate)
 Tune measurement and correction (first
First data from orbit system – looks “credible”,
test of pick-up indicated good performance
to be understood/consolidated …
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Acceleration (deceleration), injection of antiprotons … setting up of antiproton cycle
Requires electron cooler finally to be available and installed
 Requires profile monitors!
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First 100 keV beam (probably H- and/or protons) for GBAR
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Requires profile monitors!!
Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017
Thanks for your
attention !
Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017
Introduction: Antiproton Decelerator AD –
a unique facility providing 5.3 MeV antiprotons
2 Injection at 3.5 GeV/c
1 Antiproton
Production
4 Extraction
3 Deceleration and
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Start of ELENA Beam Comissioning
Location for future
ELENA installation
g
ATRAP
Co
olin
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Cooling
~1.5 1013 protons
(3.5 - 0.1 GeV/c)
(26 GeV) on target
~3.5 107 antiprotons captured in AD
 Acceptances 200 mm and ±30 10-3
Deceleration to the lowest energy 5.3 MeV
reachable “safely” (limited by mag. Fields?)
Stochastic and electron cooling at four
different energies
~3 107 antiprotons extracted per cycle
 Dense core containing
~70%
0
10 within
20 m
<1 mm, often tails up to 10 mm
 Longitudinal before bunch rotation
95% within 10-4 and 400 ns
Cycle length about 100 s
ASACUSA
Sto
c ha
stic
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7 in
( 2x10
200 ns)
ns)
(3
107 in
<300
ALPHA
Electron Cooling
Sketch of the present AD – circumference 182 m
- In addition experiment AEGIS installed
- Experiment BASE being installed
- Gbar approved to receive beam from ELENA
ABP Meeting, 20th April 2017
Introduction: Efficiency for capturing
antiprotons in traps without and with ELENA
5.3 MeV antiprotons
a shot every ~ 100 sec
to one experiment
~4 keV
antiprotons/
~ 100 sec
~ 3 x 107
Present situation with AD alone:
- Most experiments slow antiprotons down by “degrader”
=> very inefficient – most (>99%) antiprotons lost
(one experiment uses an RFQ for deceleration with higher efficiency)
100 keV antiprotons
a shot every ~100 sec
shared by ~4 experiments
~ .45 x 107
Future situation with AD and ELENA decelerating to 100 keV:
- thinner “degrader” and increased trapping efficiency
(some experiments use other means to decelerate the beam)
- Intensity shared by four exp’s allows longer periods with beam
Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017
ELENA Overview and Layout
Extraction towards existing experiments
(with fast electrostatic deflector)
Line from H- and proton
source for commissioning
Wideband RF cavity
Scraper to measure
emittances
(destructive)
Electron Cooler and
compensation solenoids
Injection with
magnetic septum (≈300 mrad)
and kicker (84 mrad)
Quadrupoles
High sensitivity magnetic
pick-up for Schottky diagnostic
(intensity) and LLRF
Extraction towards new exp. zone
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Deceleration of antiprotons from 5.3 MeV to 100 keV to improve efficiency of experiments
Circumference 30.4 m (1/6 the size of the AD)
 Fits in available space in AD hall and allows installing all equipment without particular efforts
 Lowest average field (beam rigidity over average radius) Br/R = 94 G (smaller than for AD 115 G)
Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017
ELENA Installations
(Photos from about two weeks ago)
Ring with all dipoles and
quadrupoles installed
Transfer Lines
part required for ring
commissioning
Start of ELENA Beam Comissioning
ABP Meeting, 20th April 2017