GBAR Status
• Overview
• Systems
• Installation and early commissioning
Overview
•
•
•
Goal : test Equivalence Principle with antimatter. Measure antihydrogen g with
a 1% precision.
Experimental Method : Produce antihydrogen ions (Hbar+), cooled to ~ 10uK,
photo-detach extra positron, let Hbar free fall and measure time of flight.
Systems
– Positron Source
• LINAC, positron transfer line, buffer gas trap (BGT), high field trap (MRT)
– Antiproton decelerator
– Positronium production, accumulation and Hbar+ production
– Capture Trap and Cooling, Precision trap and cooling
– Free fall detector
•
Infrastructure
Experiment Layout
LASER
1.64 µm
LINAC
e− 10 MeV
1 Be+
1 H+
∼ neV
DETECTION
W TARGET &
MODERATOR
e+ 3 eV
CAPTURE & COOLING
H + − Be+
keV H
LASERS
313 nm
Buffer Gas
e+ 1 keV
MR TRAP
Ps
ELENA
CERN-AD
p 100 keV
LASER 410 or 243 nm
DECELERATOR p keV
FOCUS
4
Experimental Area Layout
ELENA
Interaction
chamber
GBAR
Free fall vessel
GBAR
decelerator
High field trap
Buffer gas trap
AeGIS2
Linac
Y. Sacquin
SPSC - GBAR
5
LINAC
• Parameters : 9 MeV, 0.3 mA, 2-4 us bunch length, 300Hz, beam radius 0.5
mm
• Status : under test in Poland, Delivery at CERN : end November 2016
• Installation and first beam commissioning : December 2016, possibly early
January 2017
• Replace accelerating structure with final one in March 2017, and final
commissioning
L. Liszkay
e+ Target and positron line line layout
F. Butin
Target & beam line to be installed and tested after
(initial) LINAC ready
December 2016 -February 2017
Tested
successfully at
Saclay
Waiting for the final Target (setup at CERN requires a larger and water cooled target,
due to the higher power of the LINAC). Expect delivery of the final target in November, then
ready to be shipped to CERN.
7
Buffer Gas Trap
D. Van der Werf
• Assembled at Saclay
• Electrodes ready
• 2 stages ready, 3rd being
installed
• Trapping tests starting
week 45
• Delivery to CERN early
summer 2017
8
Positronium and Reaction Chamber
• Positronium production and reaction chamber (currently at Saclay)
– Chamber ready, including buncher
– Will be connected to Buffer Gas (BG) trap to test
• Focussing to the Ps cavity tube, then the buncher
• Then test Ps production, p + Ps reaction
– Refurbish existing high field trap (from RIKEN) to be inserted between BG and
reaction chamber (improve positron plasma lifetime)
– Eventually move to CERN at same time as BG (June 2017)
AntiProton Decelerator
• Under test in Orsay. 100 kV sustained achieved
• Finding a solution for sparking in surrounding air (dry air container?)
• Expected to be shipped and installed at CERN in January 2017
p from ELENA
100 keV
Δp/p=10-3
4π/6π mm.mrad
300 ns length (1.5m)
107 p /bunch
p for GBAR
1 → 6 keV
300 ns length (0.3m)
90% transmission
~ -100 kV
-10kV -95kV
~ kV
0V
ELENA transfer line optics
Agreed with ELENA team
Electrostatic deflector
• Built and presently tested in Orsay.
– To be used for the H production measurement in Saclay, then at Cern
18/01/2016
Y. Sacquin
SPSC - GBAR
11
Hbar+
First step
1 keV
H+
cooling
L. Hilico
F. Schmidt-Kaler
Capture and sympathetic Doppler cooling by laser cooled Be+ ions
In linear capture trap
2015: capture trap
(Paul trap, r0 = 3.5 mm, W = 13 MHz)
cooling Ca+/Be+
transport ions
few mm
between traps
2016: cooling of H2+
313 nm laser
with Be+/HD+ mix
(1/2 ready)
2017: transport CERN
T
÷ 3 109
Second step
> 10 000 laser cooled Be+/HD+ ions
100 neV, T ~ mK
Transfer and ground state cooling
of a Be+/H+ ion pair in the precision trap 𝛍K
tests with H2+ / H+ REMPI source
8 June 2016
P. Pérez - FRC CERN
12
Free Fall Detector
•
Tracker
– Micromegas ETHZ (Zurich)
– Present global design
• 5 planes of 3MMD, 50x50 cm2, with X-Y readout
• Spatial vertex resolution  1.5 mm
• CR background being studied
– Prototype tested in 2015
– Modules expected in second half 2017
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Scintillator Coverage
– TOF system (Seul University, Korea)
•
Initial design of Free Fall Chamber planned for December Collaboration
Meeting
Infrastructure
• Bunker
– Ready, Roof will be closed upon physical installation of the LINAC
• Experimental Area and access system
– Zone defined, shielded, access system being installed
– LINAC bunker access interlocks will be ready by time of LINAC arrival
Infrastructure
•
Services
– Racks : physically installed
– Power distribution, cable trays : being installed
– Cooling water : temporary line for LINAC available, final system early 2017
•
Safety
– Safety Documentation for LINAC installation and commissioning (permission to turn it on) in
progress
– Radiation Monitors : installed
– Collaboration with EP DSO, EN, BE DSO, HSE/RP
•
Ancillary
– Control room : available, to be equipped early 2017
– Laser Huts : design to be completed at December meeting. Installation second half 2017.
– Controls & DAQ
• Systems come with their controls, aim at integrating them in a common framework (e.g. EPICS)
• Initial “DAQ” with scope;
•
Acknowledgement : A BIG THANKS to the colleagues in EN-EA-EC (F. Butin and his
team), EP Safety (O. Beltramello and her team), BE/Safety (M. Tavlet), ELENA (C. Carli
and his team), BE-ICS-AC (B. Morand and his team).
Early Installation and Commissioning
•
Initial LINAC commissioning December 2016/early january 2017
•
Target and Positron Line
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–
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Final LINAC accelerating structure March 2017
-
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Positron line will be transported to CERN end November 2016
Target chamber waiting for delivery of tungsten target
To be installed in the shadow of LINAC commissioning
Initial commissioning (test positron production) as of January 2017
Final LINAC commissioning March / April 2017
Antiproton decelerator to CERN in January 2017
– Initial commissioning with a p gun (hydrogen stick & generator)
– Aim at taking p’s from ELENA as of ~ April, and pbar’s in the second half of the year
(when available)
Outlook
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•
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All components are covered by participating institutes
Activities at participating institutes ~ on schedule
Installation at CERN and systems commissioning
– First 6 months 2017
• LINAC
• Target & Positron Line
• Pbar decelerator (take p’s from ELENA?)
– Summer 2017
• Positron accumulation (BGT, high field trap)
• Hbar+ production chamber
– Late 2017
• Hbar+ traps and cooling
• Free fall detection
• Design of free fall chamber on critical path
– May take p’s and pbar’s from ELENA when available (> April/May)
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•
Start global commissioning in first half 2018
December Collaboration Meeting : aim at building the detailed installation and
commissioning plan