1. CAST activities and detector Developments at INP
Dr Theodoros Geralis
Institute of Nuclear Physics
Athens, 8/10/2010
The CAST experiment
The INP contribution to CAST
CAST results and prospects
Micromegas detector development
Micromegas TPC
pEDM
Nuclear Physics (Fission, Astrophysics )
Micromegas for sLHC
69th NuPECC Meeting, Athens, Greece, October 8‐9, 2010
Institute of Nuclear Physics, NCSR “Demokritos”
8/10/2010
Theo Geralis

2. Personnel Researchers CAST pEDM sLHC NuclPhys
George Fanourakis v v v v
George Daskalakis v
Theo Geralis v v v v
Kostas Kousouris (PhD) v
Eleni Ntomari (PhD) v
Sotiris Harissopoulos v
Tasos Lagogiannis v
Micael Axiotis (Post Doc) v
Technicians
Lefteris Saragas (retired) v v v v
Manolis Tsompanakis v v v v
8/10/2010
Theo Geralis

3. Signal: excess of x-rays during alignment over background
CAST axion searches
CERN Axion Solar Telescope: Axions are proposed to solve the Strong CP problem
Axion: good Dark Matter candidate
Signal: excess of x-rays during alignment over background
Production: Primakoff effect
Thermal photons interacting
With solar nuclei produce Axions.
Detection principle (Sikivie 1983)
Inverse Primakoff: axion converts to a
photon interacting with a very strong
magnetic field
Differential axion flux on Earth
Expected Number of Photons:

4. The CAST Experiment Rotating platform
Decommissioned prototype LHC dipole magnet.
Superconducting, operation at T=1.8 K.
Electric current 13,000 A.
Magnetic field: B=9T
Length: L=9.26m.
Rotating platform
( Vertical: ±8o, Horizontal: ±40o )
~90 min solar tracking during sunrise/sunset
3 X-ray detectors
X-ray Focusing Device
3He expansion volume
2 Micromegas
X-ray detectors
Micromegas
CCD+Telescope
Theodoros Geralis

5. The CAST Collaboration
CEA Saclay -- CERN -- Dogus University -- Lawrence Livermore National Laboratory
–Max-Planck-Institut for Solar System Research/ Katlenburg-Lindau –
Max-Planck-Institut für extraterrestrische Physik --Max-Planck-Institut für Physik –
National Center for Scientific Research Demokritos –NTUA Athens –
Rudjer Boskovic Institute– Institute for Nuclear Research (Moscow)–
TU Darmstadt – University of British Columbia –
University of Chicago -- Universität Frankfurt --Universität Freiburg –
University of Florida – University of Patras -- University of Thessaloniki –
Universita di Trieste –Universidad de Zaragoza -- Universität Zurich
THE GREEK CONTRIBUTION
Strong Greek contribution in the proposal and the creation of the
Collaboration (Proposal, Spokesman Prof. K. Zioutas - Univ. of Patras)
Important contributions: 1) Micromegas detectors (INP)
2)DAQ systems (INP),
3)MC simulations (INP),
4)Development of the He-3 system,
5)Novel Analysis Techniques (INP) and
6)Running the experiment
Rotating platform constructed by Greek Company
8/10/2010
Theo Geralis

6. The Micromegas principle
Spacers
h=50μm
Hole diameter=50μm, pitch=100μm
Excellent x-y resolution
Good Energy resolution
Very low background
Excellent stability
Radiation hard
Cheap
Variety of applications
(X-rays, tracking, neutron det.
TPC detector, Visible photon
det. )
Micromegas: MICRO MEsh GAseous
Structure detector

7. Goals accomplished at INP : 1) Built the first 4 Micromegas detectors, used in CAST, in collaboration with Saclay and CERN
CAST MicroMegas Assembly phase at INP
CAST MicroMegas in operation

8. Goals accomplished at INP : 2) Built the Data Acquisition systems (2) for the sunrise and the Sunset CAST Micromegas.
NIM
VME
Optical Fiber
Autopilot mode, Automatic Calibration with Fe-55, Optical Link, CASTOR
Data archiving etc

9. The PANTER tests Initial tests at the Panter X-Ray
facility MPI/MPE Munich
X-Y image of 6.4 KeV X-ray beam in Micromegas chamber (log scale for density)

10. Goals accomplished at INP : 3) Developed an Analysis package for Micromegas data
CAST has published the best axion limits over the full range of the parameter space
Apart for the microwave cavity experiments (ADMX).
WMAP
CAST
CBR
for
Prospects: 1) New Microbulk Micromegas detectors have shown extremely low
background, down to 10-7counts.kev-1cm-2s-1 . An order of magnitude
improvement in gαγγ
2) Searches in the visible using linear polarization (INP proposal).
Search for Chamaeleons.
3) Searches at the sub-keV range

11. SOME RECENT CAST PUBLICATIONS
S. Andriamonje et al., Search for 14.4-keV solar Axions emitted in the M1-Transition of Fe-57 Nuclei with CAST. JCAP 0912:002,2009.
E. Arik et al., Probing eV-scale axions with CAST. JCAP 0902:008,2009.
S. Andriamonje et al., Search for solar axion emission from 7Li and D(P,gamma)3He Nuclear Decays with the CAST Gamma-Ray calorimeter. JCAP 1003:032,2010.
The CAST experiment., J. Ruz et al., J. Phys. Conf. Ser. 110: , 2008.
5) An Improved limit on the axion-photon coupling from the CAST experiment.
By CAST Collaboration (S. Andriamonje et al., JCAP 0704: 010, 2007.
e-Print: hep-ex/
6) The X-ray Telescope of CAST. M. Kuster et al., New J. Phys. 9: 169, 2007.
e-Print: physics/
7) The Micromegas detector of the CAST experiment.
P. Abbon et al., New J. Phys. 9: 170, 2007.
e-Print: physics/
8) Prospects for the CAST Sensitivity to 14.4-keV Axions.
By CAST Collaboration (K. Jakovcic et al.), N. I. M. A580: 37-39, 2007.
e-Print: astro-ph/

12. Micromegas for sLHC
Development of Radiation hard muon detectors for super LHC
(operate at 2x105 neutrons.cm-2s-1. Tests are performed in the Tandem accelerator)
INP has built the RD51 telescope to facilitate this development
Telescope in RD51
Test beam
RD51 Telescope:
3 x-y Micromegas detectors
In the H6 SPS beam. The detectors
Were machined and built at INP
Data Acquisition system. It was
developed at INP
Telescope
Cosmics setup
8/10/2010
Theo Geralis

13. Time Projection Chamber (TPC)
Micromegas
Time Projection Chamber (TPC) x
z (t) y
Gaseous Detector
Tracking device
x, y from strips – pixels
z from tdrift i.e.
z = Vdrift . T
B field improves resolution
Micromegas advantages
Fast signals
Fast recovery
Fast ion collection
27/3/2010
Theo Geralis

14. Physics targets with Micromegas as TPC
Nuclear Physics: Fission fragments tracking
characterize neutron induced fission at
Thermal – MeV range neutrons.
(unexpolred domain)
Nuclear Astrophysics
e.g. Cross sections 4He (78Kr,γ) 82Sr
pEDM experiment (pEDM or srEDM)
Deuteron – proton Tracking to measure
Left – Right asymmetry
Axion searches (CAST)
Photoelectron tracking to allow use
of the linearly polarized X-rays.
27/3/2010
Theo Geralis

15. Fission project We concentrate on Fission project at first:
Interest: Characterize Neutron induced Fission fragments i.e.
Fission fragment properties (Mass, Charge, kinetic Energy)
Both fragments should be observed e.g.
 We need a twin detector on a back to back configuration with the
Fission target in the middle
TPC Micromegas 1 B
TPC Micromegas 2 A1
Fission Target A2
n, α
Neutron beam
27/3/2010
Theo Geralis

16. Prototype mM TPC: Design - Construction
Single TPC, only x-strips and Time readout
Aluminum Housing
32 x 1ΜΩ
Voltage Trimmer
Near mesh
Plexiglas Cage
E field shaper
Excellent work by Lefteris Saragas (Technician) at INP, NCSR Demokritos
27/3/2010
Theo Geralis

17. Tests at Saclay Initial tests Cf source 1) Sources Fe, Cd
2) Cosmics: Drift space = 8cm
3) Californium fission source:
Source support table – Drift electrode
Drift space 6cm
252Cf  nA – n – (4)A2 + (n,α)
Cf source
mM TPC
READOUT ELECTRONICS
T2K AFTER Asic Electronics
Micromegas Operating conditions:
Gas: Argon (95%) + Isobutane (5%)
Drift velocity : cm/μs
27/3/2010
Theo Geralis

18. Physics target φ = 49ο Scale ~ 200 MeV (mm)
Energy spectrum: Mesh signal
2.2 cm
1.9 cm X
Z-Time (x 40ns)
2.4 cm
φ = 49ο
Reconstructed track
Energy spectrum:
Sum of Strips’ Energy
Fragment Track length
Scale ~ 200 MeV
(mm)
27/3/2010
Theo Geralis

19. CONCLUSIONS Very significant contribution to CAST
Leading role in constructing the Micromegas,
Building the DAQs, Data Analysis
Proposal to use linear polarization for the
Future runs
Micromegas detector development at INP
extends to Physics application from Nuclear to
High Energy Physics.
Nuclear Fission, Nuclear Astrophysics
pEDM experiment
Super LHC, CAST TPC (polarization)
8/10/2010
Theo Geralis

20. BACKUP SLIDES
3/9/2019

21. Time Projection Chamber (TPC) Principle
27/3/2010
Theo Geralis

22. Micromegas for CAST
x-y plane
384 strips:
192 x +
192 y
Strips pitch =
350μm

23. THE PHYSICS DISCOVERY POTENTIAL OF CAST
CURRENTLY (and up to the end of 2010) CAST EXPLORES THE
REGION OF HIGHER AXION MASSES, UP TO ~1.2 eV
DEPENDING ON THE AMOUNT OF He-3 IN THE COLD BORES OF THE
MAGNET, CAST EXPLORES EVERY DAY A DIFFERENT AXION REST MASS
BY THE END OF 2010, CAST WILL BE THE FIRST EXPERIMENT CROSS
CHECKING THE WMAP LIMIT IN THE AXION MODELS REGION
CAST IS THE FIRST AXION HELIOSCOPE EXPLORING THE
LOW ENERGY SOLAR AXION RANGE  ~1 – 1000 eV.
EVERY DAY CAST HAS A NEW PHYSICS DISCOVERY POTENTIAL
Ongoing work & future perspectives:
Extend sensitivity into UV – EUV  experimental work
NTUA, U. Trieste & MPS /Lindau
Axion coupling to dB/dz  magn. Quadrupoles!?  theoretical work
 ( with E. Guendelman /Israel & D. Chelouche /Canada)
New Low Energy laboratory axion source  pulsed plasma: B & dB/dz
 U. Frankfurt & U. Patras
 in preparation & feasibility study