1. ELENA Overview and Layout Start of ELENA Commissioning Next Steps
Start of Beam Commissioning of the Extra Low ENergy Antiproton ring (ELENA) C. Carli on behalf of the AD/ELENA team(s) 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

2. ELENA Overview and Layout
High sensitivity magnetic Pick-up
(Schottky diagnostics for intensity, LLRF..)
Extraction towards
new experimental zone (fast deflector)
followed by el.-static transfer lines
Injection with magnetic septum and kicker
Compensation
solenoids
for (not yet
Installed) cooler
Wideband RF cavities (very similar to new
PSB cavities)
Line
From AD
Extraction towards existing experiments
Scraper to measure
emittance
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

3. Start of ELENA Commissioning – Ion Source
Aim: progress as much as possible without taking “expensive” antiprotons
Source available and tested well in advance
100 keV (post-acceleration), source a few meters from Faraday cage with HV cables in between
First tests with source mounted in Faraday cage
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
Faraday cage
Source
Thanks a lot to the team from Jülich providing source as in-kind contribution for all the efforts and flexibility
Start of ELENA Beam Comissioning ABP Meeting, 20th April 2017

4. Start of ELENA Commissioning – Transfer line
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
Source
Profile monitor prototype issues to interpret signals available since ~a month
Signals from horizontal wires
TV station almost only instrumentation available
One of the first acquisitions from November 2016
Start of ELENA Beam Comissioning ABP Meeting, 20th April 2017

5. Start of ELENA Commissioning – Ring
Beam observed over several 10s of turns (probably a few ms) in November ‘16 after less than 2 weeks
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)
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
Tunes from injection oscillations using OASIS
Synchrotron oscillation, debunching …. Seen with OASIS
Position pick-up sum signals
50 ms/div
50 ms/div
So far not conclusive – change of quad settings did not shift tunes as expected
1 ms/div
About 150 ms after injection
~ H- ???
Start of ELENA Beam Comissioning ABP Meeting, 20th April 2017

6. ELENA Commissioning – Next Steps
Get ion source up and running again
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
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 test of pick-up indicated good performance
Acceleration (deceleration), injection of antiprotons … setting up of antiproton cycle
Requires electron cooler finally to be available and installed
Requires profile monitors!
First 100 keV beam (probably H- and/or protons) for GBAR
Requires profile monitors!!
First data from orbit system – looks “credible”,
to be understood/consolidated …
Start of ELENA Beam Comissioning ABP Meeting, 20th April 2017

7. Thanks for your attention !
Start of ELENA Beam Comissioning ABP Meeting, 20th April 2017

8. Start of ELENA Beam Comissioning ABP Meeting, 20th April 2017
Introduction: Antiproton Decelerator AD – a unique facility providing 5.3 MeV antiprotons
(3 107 in <300 ns)
~ protons (26 GeV) on target
~ antiprotons captured in AD
Acceptances 200 mm and ±
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% within <1 mm, often tails up to 10 mm
Longitudinal before bunch rotation 95% within 10-4 and 400 ns
Cycle length about 100 s
Location for future
ELENA installation
Sketch of the present AD – circumference 182 m
- In addition experiment AEGIS installed
- Experiment BASE being installed
- Gbar approved to receive beam from ELENA
Start of ELENA Beam Comissioning ABP Meeting, 20th April 2017

9. 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
ELENA
~ .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

10. ELENA Overview and Layout
Extraction towards existing experiments
(with fast electrostatic deflector)
Line from H- and proton
source for commissioning
Wideband RF cavity
Injection with
magnetic septum (≈300 mrad)
and kicker (84 mrad)
Scraper to measure
emittances
(destructive)
Quadrupoles
High sensitivity magnetic pick-up for Schottky diagnostic
(intensity) and LLRF
Electron Cooler and
compensation solenoids
Extraction towards new exp. zone
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

11. 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