Latest Developments of - PowerPoint Presentation

Slide1

Latest Developments

of the CAST-IBS/CAPP Detector Project at CERN

Lino MiceliIBS Center for Axion and Precision Physics Research (IBS/CAPP)At the Korea Advanced Institute of Science and Technology (KAIST)Daejeon, Republic of Korea

13

th

PATRAS Workshop on

Axions

, WIMPs and WISPs

15-19 May 2016

Thessaloniki, Greece

IBS/CAPP

main goals in axion search2Establish state of the art axion dark matter experimental program at KAIST R&D program to improve on all experimentally accessible parametersIn addition:Promote/contribute-to international collaborations

CAPP is leading a project (CAST-IBS/CAPP project), within the CERN Solar Axion Telescope (CAST) experiment at CERN, to search for cold dark matter axions with rectangular cavities in the CAST dipole magnet.

Rectangular cavity resonant frequencies

Resonant E field aligned with the external B field:

modes

.

CAST-IBS/CAPP

search: haloscope in rectangular geometry (*)First experiment using rectangular cavities in a dipole magnet

3

(*) O

. Baker et al., Phys. Rev. D85, 035018 (2012

)

CAST-CAPP/IBS Search: The CAST Dipole Magnet

LHC prototype8.8 T field1.8 K operating temper.

9.25 m magnetic length43 mm twin boresCavity installed here in 2016Magnet front end4

2016

installed cavity: Not unable. Split design 5

6

Fundamental

mode f  6.1 GHz (25 meV) Q  10,000 (room-T)Dimensions: 138 mm X 25 mm X 23 mmMaterial: stainless steel 10-micron thick electrodeposited copper layerLongitudinally split

Magnetically

coupled

2016 Installed

Cavity

Feasibility study.

For the first time a rectangular microwave cavity was

installed and operated in a dipole magnet.We showed that an axion search experiment using the haloscope technique is sustainable in a large dipole magnet72016 Accomplishment

8

2017 Goal and challenges

Start exploiting the high volume potential offered by dipole magnetsInstallation of four tunable rectangular cavitiesPhase matchingWe can be competitive with current experiments by filling the available volume with cavitiesSome

challenges:

Unfavorable geometry, mechanical fit in the bore

, tuning

, amplifiers in high magnetic field

Mechanical fit

Cavity

design: Prof. Jhinhwan Lee, KAISTRendering: Dr. Harry Themann

Cavity positioning, anchoring, retrieving, and thermal linking

Design by Prof.

Hyoungsoon

Choi, KAIST

Cavity inside the CAST magnet bore

(wiring representation not current)

10

Test cavity (Cu)

Actual cavity ( SS-316L, not yet plated)

Piezo + holder

Cavity tuning: dielectric

‘Locomotive” tuning

Pneumatically Tuned (Accordion)

Cavity The cavity will be tuned by changing the pressure (± 300 mbar) of He process gasExpanding and compressing a bellows on the cavity mid-plane changes the frequency by > 1GHzBecause no current flows on the mid-plane the bellows have negligible effect on the cavity Q The loss tangent of He a low temperature is extremely low, Tan(δ) < 10-11 (*)

Joseph Mike Brennan (BNL)(*) RF Performance of a Superconducting S-Band Cavity Filled with Liquid Helium, W. Hartung et al., LINAC 2006, Knoxville, Tn

The Cavity Can be Split on the Mid-plane because there are no Currents there

No current in cavity mid-plane

Electric field in the TM010 modeJoseph Mike Brennan (BNL)

Bench Test of Accordion Cavity

Pressure measurement. Only a few psi is needed.This cavity is tuned with air pressure

Joseph Mike Brennan (BNL)

Results of Frequency Change with pressure

S21 measurements, 2 GHz spanYellow trace positive pressure, +3 psiMagenta trace is negative pressure, -5 psiJoseph Mike Brennan (BNL)

Cavity frequency vs pressure differential

Exploring original ideas, revisiting established ideas.

A new learning step in 2017 and, hopefully, some physics information.

Split cavityWe are pleased to see that it is now adopted by othersImpedance vs noise matchingThe radiometer equation and its applicabilityMultiple cavitiesPhase matching/lockingElimination of correlated noiseMultiplexed high speed acquisitionDAQ

I/Q

streaming (time domain)

Some comments and suggestions by Fritz

CaspersNoise matching. For cavity type experiments which are NOT  operating in the single photon regime (i.e. everything above a few

deg K) , the concept of noise matching is highly important. In particular this means NOT to insert isolators/circulators between the cavity output and the first LNA but rather adjust the cable length there (antenna output to preamp) for optimum noise match (one can gain up to several dB in effective S/N ratio).Recently also colleagues from the accelerator community (IMP) learned about the benefits of this concept for faint Schottky signal pickup cavities .[c.f. also "noise figure contours" in the Smith chart]The radiometer concept and related issues. The use of the radiometer formula is very common for sensitivity calculations in the DM community. However the rather generic radiometer formula assumes implicitly the use of either a Dicke type or correlation type radiometer. These days for satellite applications usually correlation type radiometers are in operation since they avoid the spikes from the Dicke Switch. For DM detection application I have seen so far only " total power"  style radiometer configuration which are suffering from long term gain drifts in the amplifier chain.Those long term gain drift are compensated in "REAL" radiometers due to the permanent autocalibration (Old days:Dicke Switch) down to a level of a few micro Decibel. Of course we hear  then the argument..yes we do have a  permanent gain calibration..its the pilot tone..This help a bit, but its miles away from a good Dicke or correlation radiometer.

If

we go for noise temp measurement in terms of

axion

search we need to have effective sensitivities in the ballpark of a few micro

deg

K which is not the case in the real DM world so far (but operational in space since decades and also used in radioastronomy on earth) If we go for individual "spike "detection in the cavity we should use (numerical or hardware implemented) "Matched filters" like in radar technology for a particular signal shape (c.f. spread spectrum technology, detecting signals which are normally completely invisible in the noise). In short: DO use correlations radiometer techniques ....(its better than Dicke ones and much better than total power radiometers , applied so far in DM search)

18

Sensitivity projections

IBS/CAPP

Yannis SemertzidisJihoon Choi Woohyun Chung Young-Im KimMiran KimByeongRok KoMyeongJae Lee Soohyung LeeLino Miceli

SungWoo Youn Harry Themann 19CAST-IBS/CAPP project collaborators / consultants

CAST/CERN

Konstantin

Zioutas

Martyn Davenport

Wolfgang FunkJean-Michel LaurentAntonios GardikiotisTheodoros Vafeiadis

KAIST

Hyoungsoon Choi Jhinhwan LeeKRISSYonuk Chong

CERN

Michael Betz

Fritz

Caspers

Lucio

Fiscarelli

Carlo

Petrone

Manfred Wendt

Walter

Wuensch

BNL

Joseph M. Brennan

Frank Lincoln