PHASM201 Project Presentation: Measuring the Muon's Dipole ...lukicov/files/project_talk_Gleb_Lukicov.pdf · electronics: frontend (ASDQ, TDC) and backend (GLIB). Final Product: a

PHASM201 Project Presentation:Measuring the Muon’s Dipole Moments with the

Fermilab g-2 Experiment (E989)Investigation of the Tracking Detector

Gleb Lukicov

4th Year MSci PhysicsDepartment of Physics and Astronomy

University College London

Supervisor: Prof. Mark Lancaster

17 March 2016

Gleb Lukicov PHASM201: Project Presentation 17 March 2016 1 / 30

Outline

1 Introduction to ProjectAims and ObjectivesMotivation

2 Introduction to Muon Physics and the g-2 ExperimentPhenomenological Overview of the Dipole Moments of the MuonExperimental Methodology of g-2Tracking Detector

3 Achieved Results


IntroductionAims and Objectives

Aim

To develop software and hardware solutions to gain a better understandingof the tracking detector for the Fermilab g-2 experiment (E989).

Objectives

1 To analyse the June 2015 testbeam data.2 To develop and test the frame assembly.3 To investigate the efficiency of the tracker using the developed

assembly.


IntroductionMotivation

Motivation for the Fermilab g-2 experiment (E989) [1].

The muon magnetic dipole moment (MDM) allows to probe for physicsbeyond the Standard Model (BSM), such as supersymmetry (SUSY)and extra dimensions.

An observation of an electric dipole moment (EDM) of the muonwould provide a new source of charge-parity (CP) violation, which canhelp to explain the matter-antimatter asymmetry in the Universe.

Motivation for the project

Provide an input into understating the response of the trackingdetector’s, which is required to measure the muon’s EDM and MDMprecisely.

[1] J. Grange, et al. (FNAL E989 g-2 Collaboration), Muon (g-2) Technical Design Report, (2015) arXiv:1501.06858


http://arxiv.org/abs/1501.06858

The Standard ModelIntroduction to Muon Physics

Image courtesy of PBS Nova.


Muon DecayIntroduction to Muon Physics

Muon is ∼200 times heavier than an electron.

Lifetime is ∼ 2.19 µs in vacuum - longest of all unstable elementaryparticles.

Parity violating decay - preferential emission of the highest energypositrons along muon’s spin [2].

µ+ → e+ + νe + νµ (1)

�νµ

e+

µ+ W+ νe

[2] M. Thomson, Modern Particle Particle Physics, 1st ed. (Cambridge University Press, England, 2013).


Magnetic Dipole MomentTheory

The magnetic dipole moment (MDM) is given [3] by

µ = gµ

(q

2mµ

)s, (2)

where gµ is the gyromagnetic ratio of the muon. While the anomalous magnetic moment(AMM) is given by

aµ =gµ − 2

2. (3)

Defining aµ this way allows for eq. (2) to be written in the form

µ = (1 + aµ)

(q

2mµ

)s, (4)

clearly showing the AMM influence on the muon MDM. The current calculation [4] of aµis 0.00116591803(49), with 440 ppb precision - achieved by considering 12’000 Feynmandiagrams (!) with up to 6 vertices.

[3] P. Dirac, The Quantum Theory of the Electron. Proc. R. Soc. A 117, 610 (1928).

[4] K. Olive et al., (Particle Data Group), Review of Particle Physics. Chin. Phys. C 38, 090001 (2014).



The MDM arises from the interaction of the muon with photons, with the anomaly givenby αSM

µ = αQEDµ + αEW

µ + αHadronµ [5].

�γ

µ− µ− �γ

γ

µ− µ−�γ

γ

e−

γ

e+

µ− µ−

The BSM interaction which can affect muon’s MDM is shown below, with AMM given byαµ = αSM

µ + αSUSYµ .

�µ−

µ−

χ◦

µ−

µ−

γ

[5] B. Roberts and W. Marciano, Lepton Dipole Moments, edited by B. Roberts and W. Marciano (World Scientific,Singapore, 2010).



The difference between the Brookhaven g-2 (E821) experiment [6] (540 ppb precision)and theory (440 ppb precision) is given by

δaµ = aexperimentµ − aSMµ = 288(80)× 10−11, (5)

which corresponds to a 3.6σ deviation. Fermilab g-2 experiment (E989) aims for a 5σfinal result, with 140 ppb precision, by 2019.

[6] G. Bennett et al., (BNAL E821 g-2 Collaboration), Final Report of the Muon E821 Anomalous Magnetic MomentMeasurement at BNL. Phys. Rev. D 73, 072003 (2006). Image courtesy of the g-2 Collaboration [1].


Electric Dipole MomentTheory

The muon EDM is given [7] by

d = η

(q

2mµ

)s, (6)

where η = me

4dc~ .

The total Hamiltonian for a spin-1/2 particle in applied magnetic (B) andelectric (E ) fields is given by

H = −µ · B − d · E . (7)

Both P and T symmetries are violated by d ·E term. The SM value for themuon EDM [8] is (1.4± 1.5)× 10−25 e·cm, while the proposedexperimental (E989) capability is 1.8× 10−21 e·cm.

[7] P. Dirac, The Quantum Theory of the Electron. Part II. Proc. R. Soc. A 118, 351 (1928).

[8] G. Bennett et al., Improved Limit on the Muon Electric Dipole Moment. Phys. Rev. D 80 (2009).


MDM MeasurementMethodology of g-2

The AMM measurement through the precession frequency

ωa = −aµe

mµB. (8)

Image courtesy of the g-2 Collaboration [1].


MDM Measurementg-2

The number of detected electrons above 1.8 GeV (3.6× 109 e− total)during the final run of E821 [6] in 2001.

The fit and data are shown.



EDM Measurement and Tracking Detectorg-2

The tracker can provide an EDM measurement through the vertical asymmetry of thepositron decay

ωaη =√ω2a + ω2

η = ωa

√1 +

(ηβ

2aµ

). (9)

Hence the precession plane is tilted by a small angle δ, where

δ = tan−1

(ωη

ωa

)= tan−1

(ηβ

2a

). (10)

Images courtesy of the g-2 Collaboration [1].


Tracking Detectorg-2

The trajectory of the decay positron: through the tracker station of 8detector units; and through an individual straw.

The gas composition in straws is 1:1 Ar:Ethane

Central cathode wire is at +1.8 kV.

Images courtesy of the g-2 Collaboration [1].


MWPC Data AnalysisProject Results

Simulating conditions (beam RMS, Multi-Wire Proportional Chamber (MWPC)separation, etc.) during June 2015 testbeam to estimate resolution of MWPC protondata:

Combined results of 106 Simple Linear Regression (SLR) fits for trajectories (actualposition) vs projected hits in the tracking detector.

Therefore, the final simulated value of the resolution of MWPC data is

σ =√Variance = 152.1(1) µm. (11)


Detector Testing SystemProject Results

Developed a motorised platform to move across the active area of thetracking detector.



SiPM(Silicon Photomultiplier)-scintillator system with thestrontium-90 source mounted on the mobile platform.



Testing of the SiPM-scintillator system with the strontium-90 (As=2.75MBq; E = 0.94 MeV) source, with different parameters (input voltage,threshold, etc.).

1 Model: MicroFB-SMA-30035. B-Series: Sensor, (Sensl Ltd.), (2015)http://www.sensl.com/downloads/ds/DS-MicroBseries.pdf (visited on 08/01/2016).


http://www.sensl.com/downloads/ds/DS-MicroBseries.pdf

SimulationProject Results

Implementing strontium-90 (As=2.75 MBq) source in Geant4:1 Randomising starting position on the disk (r, θ).2 Randomising energy distribution (via Monte Carlo methods).3 Angular distribution: straight tracks only (physically constrained by aluminium

collimator).4 Vetoing candidate particle events to record and track only the relevant events (i.e.

events able to leave the collimator) at 2.75 MBq.

Geometry and particle gun (strontium-90) implemented to simulate data, which will havethe same structure as the real data.





Example of an ideal event, registering hits in all 4 straws (in a layer) andthe scintillator is displayed below. Simulated data from 1000 events throughthe straws is also shown.


Hardware SolutionProject Results

Integration of the SiPM-scintillator system with tracking detector’selectronics: frontend (ASDQ, TDC) and backend (GLIB).

Final Product: a hardware solution (consisting of a motorised frame,scintillator-SiPM detector mounted on a mobile C-shape arm, FE/BEelectronics, and simulated data for comparison) to be used to testefficiency of the tracking detector.


References

[1] J. Grange, et al. (FNAL E989 g-2 Collaboration), Muon (g-2) Technical DesignReport, (2015) arXiv:1501.06858

[2] M. Thomson, Modern Particle Particle Physics, 1st ed. (Cambridge UniversityPress, England, 2013).

[3] P. Dirac, The Quantum Theory of the Electron. Proc. R. Soc. A 117, 610 (1928).

[4] K. Olive et al., (Particle Data Group), Review of Particle Physics. Chin. Phys. C38, 090001 (2014).

[5] B. Roberts and W. Marciano, Lepton Dipole Moments, edited by B. Roberts andW. Marciano (World Scientific, Singapore, 2010).

[6] G. Bennett et al., (BNAL E821 g-2 Collaboration), Final Report of the MuonE821 Anomalous Magnetic Moment Measurement at BNL. Phys. Rev. D 73, 072003(2006).

[7] P. Dirac, The Quantum Theory of the Electron. Part II. Proc. R. Soc. A 118, 351(1928).

[8] G. Bennett et al., Improved Limit on the Muon Electric Dipole Moment. Phys.Rev. D 80 (2009).


http://arxiv.org/abs/1501.06858

Appendices

1 Beamlines at Fermilab

2 SiPM outputs

3 Beta Energy Considerations

4 Signal Processsing in ASDQ

5 MWPC Data Analysis


Appendix 1: Beamlines at FermilabMethodology of g-2

The source of muons are pions, which are produced by sending a 8.91 GeV proton beamon a (lithium) production target:

p + p(target)(n(target))→ p + n + π+(π−), (12)

The produced (3.11 GeV) pions then decay into longitudinally polarised muons.

π(∓) → µ(∓) + νµ(νµ). (13)



SiPM: FAST vs SLOW output

The comparison between FAST and SLOW outputs of the SiPM.


Appendix 2: Beta Energy

The energy of electrons from yttrium-90 [A.1].

[A.1] R. Budnitz, Strontium-90 And Strontium-89: A Review Of Measurement Techniques In Environmental Media. ActaRadiologica 14, 302 (1964).


Appendix 3: Signal Processing in ASDQ

The ASDQ signal processing chain [A.2].

[A.2] W. Bokhari et al., The ASDQ ASIC for the Front End Electronics of the COT, (1999)www-ese.fnal.gov/btev/electronicsprojects/customics/ASDQ-new.ps (visited on 23/02/2016).


www-ese.fnal.gov/btev/electronicsprojects/customics/ASDQ-new.ps

Appendix 4: MWPC Data AnalysisProject Results

MWPC 1 hit spatial distribution in y plane is shown below.

Individual Time-to-Digital Converter (TDC) performance for channels and time is shownbelow.


Appendix 4: MWPC Data AnalysisProject Results

Multiple Hits Resolution (work in progress):


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PHASM201 Project Presentation: Measuring the Muon's Dipole ...lukicov/files/project_talk_Gleb_Lukicov.pdf · electronics: frontend (ASDQ, TDC) and backend (GLIB). Final Product: a