Axion searches with CAST: latest results andresults and prospects · 2020. 9. 9. · Solar AxionsSolar Axions Sl i d db hSolar axions produced by photonoton--toto--axion conversion

Axion searches with CAST: latest results and prospectslatest results and prospects

Igor G IrastorzaUniversidad de Zaragozag

I t ti l M tiI t ti l M ti F d t l Ph iF d t l Ph iInternational Meeting International Meeting onon Fundamental PhysicsFundamental PhysicsCanfranc, Huesca, Canfranc, Huesca, SpainSpain, , FebruaryFebruary 10th 10th 20112011

AXION motivationAXION motivation

Strong CP problem: why strong interactions seem not to violate CP?– CP violating term in QCD is not forbidden But neutron– CP violating term in QCD is not forbidden. But neutron

electric dipole moment not observed.

Natural answer if Peccei-Quinn mechanism exist.N U(1) l b l t t l b k– New U(1) global symmetry spontaneously broken.

PRIMAKOFF

As a result, new pseudoscalar, neutral and very light particle is predicted, the axion.It couples to the photon in every model

EFFECTIt couples to the photon in every model.

Winter Meeting, Canfranc, Feb 2011

Igor G. Irastorza / Universidad de Zaragoza

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AXION motivation: CosmologyAXION motivation: CosmologyAXION motivation: CosmologyAXION motivation: CosmologyAxionsAxions are produced are produced in the early Universe by a in the early Universe by a pp y yy ynumber of processes:number of processes:–– AxionAxion realignmentrealignment–– Decay of Decay of axionaxion stringsstrings–– Decay of Decay of axionaxion wallswalls

NONNON--RELATIVISTICRELATIVISTIC(COLD) AXIONS(COLD) AXIONS

In general, In general, Range of Range of axionaxion masses of masses of 1010--66 –– 1010--33 eVeV are of are of interest for the interest for the axionaxion to be the (main component of the) to be the (main component of the) CDMCDM..

–– Thermal productionThermal production RELATIVISTICRELATIVISTIC(HOT) AXIONS(HOT) AXIONS

In order to have substantial relativistic In order to have substantial relativistic axionaxion density, the density, the axionaxion mass must mass must be close to 1 be close to 1 eVeV. (. (ma >1.02 ma >1.02 eVeV gives densities too much in excess to be gives densities too much in excess to be compatible with latest CMB data)compatible with latest CMB data) Hannestad et al, JCAP 0804 (2008) 019 [0803.1585 (astro-ph)]



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Solar AxionsSolar AxionsSolar AxionsSolar AxionsS l i d d b hS l i d d b hSolar axions produced by photonSolar axions produced by photon--toto--axion conversion of the solar plasma axion conversion of the solar plasma photonsphotons

Solar axion flux [van Bibber PRD 39 (89)] [CAST JCAP 04(2007)010]

Solar physics+

Primakoff effectPrimakoff effect

Only one unknownparameter gaγ

Axion Helioscope principleAxion helioscope [Sikivie, PRL 51 (87)]Axion helioscope [Sikivie, PRL 51 (87)]

Axion Helioscope principle

AXION PHOTON CONVERSION



5Igor G. Irastorza / Universidad de Igor G. Irastorza / Universidad de ZaragozaZaragoza COHERENCE 1

HelioscopesHelioscopesHelioscopesHelioscopesPrevious helioscopes: Previous helioscopes: –– First implementation at Brookhaven (just few hours of data) [Lazarus et First implementation at Brookhaven (just few hours of data) [Lazarus et

at. PRL 69 (92)]at. PRL 69 (92)]

–– TOKYO Helioscope (SUMICO): 2 3 m long 4 T magnetTOKYO Helioscope (SUMICO): 2 3 m long 4 T magnetTOKYO Helioscope (SUMICO): 2.3 m long 4 T magnet TOKYO Helioscope (SUMICO): 2.3 m long 4 T magnet

Presently running: Presently running:


6–– CERN Axion Solar Telescope (CERN Axion Solar Telescope (CASTCAST) )

CAST experiment @ CERNCAST experiment @ CERNppDecommissioned LHC test magnet (L=10m, B=9 T)Moving platform ±8°V ±40°H (to allow up to 50 days / year of alignment)4 magnet bores to look for X rays

LHC test

3 X rays detector prototypes being used.X ray Focusing System to increase signal/noise ratio.

LHC test magnet

TPC (

CAST experiment @ CERNCAST experiment @ CERNCAST experiment @ CERNCAST experiment @ CERN

Micromegas

TPC inside shielding(Running until 2007) X-ray telescope CCD



8Igor G. Irastorza / Universidad de Igor G. Irastorza / Universidad de ZaragozaZaragoza

New Micromegas detectors for CASTNew Micromegas detectors for CASTSince 2008 2 new Micromegas detectors replaced the TPC indetectors replaced the TPC in the sunset side.– Better shielding

At sunrise side The MicromegasAt sunrise side. The Micromegas detector substantially upgraded:– microbulk, shielding, monitoring,

frontal calibration flow controllerfrontal calibration, flow controller,

In overall increasingly better backgrounds & sensitivity

SunsetMicromegas

SunriseMicromegas



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CAST XCAST X ray telescoperay telescopeCAST XCAST X--ray telescoperay telescopeCAST CAST innovationinnovation of the “helioscope concept” of the “helioscope concept”

WolterWolter I I typetype grazinggrazing incidentincident opticsoptics ((prototypeprototypefor ABRIXAS for ABRIXAS missionmission))FromFrom ØØ43 mm (43 mm (magnetmagnet bore)bore) ØØ3 mm spot3 mm spotFromFrom ØØ43 mm (43 mm (magnetmagnet bore) bore) ØØ3 mm spot3 mm spot

improvesimproves signalsignal to to backgroundbackground ratioratio



10Igor G. Irastorza / Universidad de Igor G. Irastorza / Universidad de ZaragozaZaragoza

CAST XCAST X ray telescoperay telescopeCAST XCAST X--ray telescoperay telescope

Spot from the telescope on Spot from the telescope on the CCD detectorthe CCD detector

Tracking data Signal simulation

Determination of the spot Determination of the spot position by calibrations and position by calibrations and precise alignment of precise alignment of t lt ltelescope.telescope.Counts inside the spot Counts inside the spot compatible with compatible with background levelbackground levelbackground levelbackground level



Igor G. Irastorza / Universidad de Igor G. Irastorza / Universidad de ZaragozaZaragoza 1111

CAST phase II CAST phase II –– principle of detectionprinciple of detection

axionsTransverse magnetic field (B)

X ray

X raydetector

axionsTransverse magnetic field (B)Transverse magnetic field (B)

X ray

X raydetector

X ray

X raydetector

X ray

X raydetector

L

A

L

A

Extending the coherence to higher axion masses...Cohe ence condition (qL

CAST: dataCAST: data takingtaking statusstatusCAST: data CAST: data takingtaking statusstatusYEARS PHASE Main Publications

2003 –2004

CAST phase I• vacuum in the magnet bores

COMPLETED • PRL 94 (2005) 121301• JCAP 0704 (07) 010

2006 CAST phase II - 4He Run• axion masses explored up to 0.39 eV(160 P-steps)

COMPLETED • JCAP 0902 (09) 008

2008 -2011

CAST phase II - 3He Run• axion masses to be explored up to

ONGOING In preparation

p p1.20 eV• currenty ~700 steps performed

Hi h E A i D t t ki ith JCAP 1003 032 2010In parallel- parasitic

•High Energy Axions: Data taking with a HE calorimeter•14.4 keV Axions: TPC data•Low Energy (visible) Axions: Data t ki ith PMT/APD ()

• JCAP 1003:032,2010(arXiv:0904.2103)• JCAP 0912:002,2009 (arXiv:0906.4488)• arXiv:0809.4581



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taking with a PMT/APD. ()

CASTCAST latestlatest publishedpublished limitlimitCAST CAST latestlatest publishedpublished limitlimitCAST CAST

Phase IIPhase II

CASTCAST

He4 RunHe4 Run

CAST CAST Phase IPhase I

JCAP 0704 (07) 010

JCAP 0902 (09) 008Prospects for the Prospects for the ongoing He3 Runongoing He3 Run

Current progress Current progress ~ 0.9 ~ 0.9 eVeV

QCD i d l i i t d !!QCD i d l i i t d !!Winter Meeting, Canfranc, Feb 2011


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QCD axion models region is entered !!.QCD axion models region is entered !!.

PreliminaryPreliminary 33HeHe resultsresultsPreliminaryPreliminary 33He He resultsresults

A very-preliminary result including 3 y p y gMicromegas detectors. CCD data not

included yet.

Axion mass 0 39 0 65 eV excludedAxion mass 0.39 – 0.65 eV excludeddown to 2-3 x 10-10 GeV-1

Full publication being prepared



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FutureFuture prospectsprospectsFutureFuture prospectsprospects

CAST Near CAST Near term future:term future:–– CAST will revisit phase I (and possibly phase II He4) CAST will revisit phase I (and possibly phase II He4)

with better detectors with better detectors better sensitivity. better sensitivity. –– Search in parallel for exotica: Search in parallel for exotica: chamaleonschamaleons, , paraphotonsparaphotons, non , non

standard axions (visiblestandard axions (visible wavelenghtswavelenghts))standard axions (visible standard axions (visible wavelenghtswavelenghts))

Longer term future:Longer term future:Longer term future: Longer term future: –– Studies for a new generation axion helioscope (>1 Studies for a new generation axion helioscope (>1

order of magnitude more sensitive than CASTorder of magnitude more sensitive than CAST))order of magnitude more sensitive than CASTorder of magnitude more sensitive than CAST))New projectNew project



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TowardsTowards a new a new generationgenerationaxion helioscopeaxion helioscope

Ingredients of a successful helioscope

CAST is established as CAST is established as a reference a reference result result in experimental axion physics (*)in experimental axion physics (*)CAST PRL2004 most cited experimentalCAST PRL2004 most cited experimental

Ingredients of a successful helioscope

CAST PRL2004 most cited experimental CAST PRL2004 most cited experimental paper in axion physicspaper in axion physicsNo other technique can realistically No other technique can realistically improve CAST in a wide mass range.improve CAST in a wide mass range. Large & powerful magnet...p gp g

Next step in the Next step in the field field new new generation generation axionaxion helioscopehelioscope

X ray opticsgg pp

CAST has shown the way to improve CAST has shown the way to improve the helioscope technique…the helioscope technique…

...X-ray optics,...

p qp q

...and low background detectors



Igor G. Irastorza / Universidad de Igor G. Irastorza / Universidad de ZaragozaZaragoza 1717

...and low background detectors

AxionAxion HelioscopesHelioscopes FOMFOMAxion Axion HelioscopesHelioscopes FOMFOM

3 3 elementselements drive the drive the sensitivitysensitivity of of anan axion helioscopeaxion helioscope

MAGNETX-RAYOPTICSX-RAY OPTICSDETECTORS



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NewNew magnetmagnetNew New magnetmagnetCAST j f h b i iCAST j f h b i iCAST enjoys one of the best existing CAST enjoys one of the best existing magnets than one can “recycle” for axion magnets than one can “recycle” for axion physics (LHC test magnet)physics (LHC test magnet)Only way to make a step further is to Only way to make a step further is to built a new magnet, specially conceived built a new magnet, specially conceived for thisfor thisfor this.for this.Work ongoing, but best option up to Work ongoing, but best option up to know is a know is a toroidal configuration:toroidal configuration:–– Much bigger aperture than CAST: ~1 m Much bigger aperture than CAST: ~1 m

per boreper bore–– Lighter than a dipole (no iron yoke)Lighter than a dipole (no iron yoke)–– Bores at room temperatureBores at room temperature Cross section of the magnet



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XX ray opticsray opticsXX--ray opticsray opticsDuring the last four decades the xDuring the last four decades the x rayrayDuring the last four decades, the xDuring the last four decades, the x--ray ray astronomy community has devoted billions of astronomy community has devoted billions of dollars to develop reflective xdollars to develop reflective x--ray ray opticsoptics

Innovations include:Innovations include:–– Nested designs (so calledNested designs (so called WolterWolter telescopes)telescopes)

XMM-Newtontelescope with 56

nested shellsNested designs (so called Nested designs (so called WolterWolter telescopes)telescopes)–– LowLow--cost substratescost substrates–– Highly reflective coatingsHighly reflective coatings

Although Although NGAH will require fabrication of NGAH will require fabrication of dedicated optics, it will be crucial todedicated optics, it will be crucial to leverageleverage Ni dedicated optics, it will be crucial to dedicated optics, it will be crucial to leverage leverage as much infrastructure as possible to minimize as much infrastructure as possible to minimize cost and riskscost and risks

E = 4.5 keVσ = 0–20 Å

One possibility: thermallyOne possibility: thermally--formed formed l bl bglass substratesglass substrates

NASA is currently buildingNASA is currently buildingNASA is currently building NASA is currently building NuSTARNuSTAR, a hard x, a hard x--ray telescoperay telescope

NuSTARNuSTAR uses thin glassuses thin glassNuSTARNuSTAR uses thin glass uses thin glass substrates coated with substrates coated with multilayersmultilayersto enhance reflectivity up to 80 to enhance reflectivity up to 80 keVkeVkeVkeV

The specialized tooling to shape The specialized tooling to shape the substrates and assemble thethe substrates and assemble the

NuSTAR optics assembly machine

the substrates and assemble the the substrates and assemble the optics will be available after optics will be available after NuSTARNuSTAR is launched in 2012is launched in 2012

Hardware can be easily Hardware can be easily configured to make optics with a configured to make optics with a

i t f d i d ii t f d i d ivariety of designs and sizesvariety of designs and sizes NuSTARtelescope

NewNew detectorsdetectorsNew New detectorsdetectorsLatestLatest Micromegas: x20Micromegas: x20History of background improvement of Micromegas detectors at CAST LatestLatest Micromegas: x20 Micromegas: x20 improvedimproved backgroundbackground–– ShieldingShielding

Micromegas detectors at CAST

Nominal values at CAST 2003

20042006

–– RadiopurityRadiopurity. New . New manufacturingmanufacturing techniquetechnique(microbulk(microbulk readoutsreadouts))

2006

2008-10

(microbulk (microbulk readoutsreadouts))–– More More powerfulpowerful offline offline cutscuts

Ultra low background periods



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NewNew detectorsdetectorsNew New detectorsdetectorsVeryVery activeactive developmentdevelopment ononHistory of background improvement of Micromegas detectors at CAST VeryVery active active developmentdevelopment ononlowlow backgroundbackgroundTestsTests in in controlledcontrolled conditionsconditions

Micromegas detectors at CAST

Nominal values at CAST 2003

20042006

undergroundunderground at Canfranc:at Canfranc:–– BetterBetter shieldingshielding coveragecoverage

2006

2008-10

–– ThickerThicker shieldingshielding

Tests at

BBackgroundsackgrounds around 5x10around 5x10--77c/c/keVkeV/s/cm2, with improved/s/cm2, with improved

Tests at Canfranc (2010)

c/c/keVkeV/s/cm2, with improved /s/cm2, with improved shielding, ~ x10 better than CASTshielding, ~ x10 better than CAST

Ultra low background periods



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Tests at CanfrancTests at CanfrancTests at CanfrancTests at CanfrancCAST replica CAST replica takingtaking data in Canfranc. data in Canfranc. GoalsGoals::–– StudyStudy backgroundbackground limitationslimitations underunder controlledcontrolled conditionsconditions–– Tests Tests solutionssolutions for for improvementimprovement. .

C tC t i l tii l ti–– Compare to Compare to simulationssimulationsBackgrounds around 5x10-7 c/keV/s/cm2

with improved shielding~ x10 better than CAST

Many lessons being learnt...



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NewNew designdesignTightvessel

CoppertubeNew New designdesign

AA d id i b ib i d fi dd fi dA new A new designdesign beingbeing defineddefined, , applyingapplying the the lessonslessons learnedlearned..–– BetterBetter shieldingshielding ((compactnesscompactness))–– TightnessTightness ((radonradon))–– CleanerCleaner materialsmaterials. . –– BetterBetter driftdrift fieldfield..

CopperplateSignals

feedthroughs

–– ElectronicsElectronics withwith 3D 3D infoinfo–– AcitveAcitve ((anticomptonanticompton) ) shieldingshielding

PreliminaryPreliminary considerationsconsiderations pointpointthatthat anticomptonanticompton shouldshould givegiveanotheranother x10 factorx10 factoranotheranother x10 factor.x10 factor.

GoalGoal: : below 10below 10--77 c/c/keVkeV/s/cm/s/cm22Driftcage

Micromegasreadout



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How much beyond CAST we can hope for?How much beyond CAST we can hope for?How much beyond CAST we can hope for?How much beyond CAST we can hope for?

Factor 8 to 30 Factor 8 to 30 betterbetter in in ggaaγγ (4000 to 10(4000 to 1066 in in signalsignal strengthstrength!!)!!)signalsignal strengthstrength!!)!!)

Conservative scenario

Realistic scenario

Optimistic scenarios



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How much beyond CAST we can hope for?How much beyond CAST we can hope for?How much beyond CAST we can hope for?How much beyond CAST we can hope for?

Much largerQCD axion region explored

Helioscope prospects

Astrophysicalhints for ALPs

In combination with dark matter axion searches a big part of the QCD axion

d l ld b

p p p

model region could be explored next decade.

The cooling of white dwarftsThe cooling of white dwarftsThe cooling of white dwarftsThe cooling of white dwarftsLuminosityLuminosity functionfunction ((WD’sWD’s per per unitunit

(Isern et al. 2008,2010)

magnitudemagnitude) ) alteredaltered byby axion axion coolingcoolingClaimClaim of of detectiondetection of new of new coolingcoolingmechanismmechanism ((IsernIsern 2008)2008)(( ))AxionAxion--electronelectron couplingcoupling of ~1x10of ~1x10--1313(( axion axion massesmasses of 2of 2--5 5 meVmeV ororlargerlarger) ) fitsfits datadata..gg ))

DFSZ axion (cosβ=1)



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DFSZ axion (cosβ 1)

The cooling of white dwarftsThe cooling of white dwarftsThe cooling of white dwarftsThe cooling of white dwarftsmeVmeV massesmasses seemseem outout of of reachreach of of eveneven anan improvedimproved axionaxionhelioscopehelioscope… BUT… BUTAxionAxion--electronelectron couplingcoupling providesprovides

EXTRA bremstrahlungemission ~50 times larger than standardPrimakoff emission

extra extra axionaxion emissionemission fromfrom thetheSunSun……Extra Extra emissionemission concentratedconcentrated at at lowerlower energiesenergies (~1 (~1 keVkeV))

SuchSuch axion axion couldcould produce a produce a detectabledetectable signalsignal in the newin the new Courtesy of G. Raffelt and J. Redondodetectable detectable signalsignal in the new in the new axion helioscopeaxion helioscope

Courtesy of G. Raffelt and J. Redondo

Studies ongoing…



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And moreAnd moreAnd more…And more…

Helioscope prospects

How to access thisi ??region??

Detecting relicaxions…



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ConclusionsConclusionsCAST progressing as expected. Well into its 2nd phase:– He-4 results published.e esu ts pub s ed– He-3 data taking ongoing. Preliminary result presented.

No axion found so far. Relevant parameter space excluded. – Compatible with best astrophysical limitsp p y– Entering realistic QCD axion model band for the first time.– Byproducts: high energy axions, low energy (visible E) axions, 14 keV

axions from nuclear transitions,…CAST is established as a reference result in axion physics. Expertise gathered in magnet, optics, low back detectors

Towards a new generation axion helioscope: feasibility study in progress. Good prospects at the moment…In combination with dark matter axion searches (ADMX) a big part( ) g pof the QCD axion model region could be explored next decade.White dwarfts e-coupled axions?, relic axions?, ALPs?… towards anaxion observatory



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Documents

Axion searches with CAST: latest results andresults and prospects · 2020. 9. 9. · Solar AxionsSolar Axions Sl i d db hSolar axions produced by photonoton--toto--axion conversion