MESA - Mainz Energy Recovery Superconducing Acclerator - - PowerPoint PPT Presentation

EXPERIMENTS WITH INTERNAL TARGETS AT THE MAINZ ENERGY-RECOVERING SUPERCONDUCTING ACCELERATOR

Harald Merkel

Johannes Gutenberg-Universit¨ at Mainz

54th International Winter Meeting on Nuclear Physics

Bormio (Italy), January 27th, 2016

The MESA Accelerator MAGIX High resolution magnetic spectrometers Internal targets: Gas Jet Target or Polarized Target Physics program Magnetic radius of the proton Astropyhsical S-Factor Few body physics Search for exotic particles Summary

Harald Merkel, Bormio 2016 2/19

MESA - Mainz Energy Recovery Superconducing Acclerator

Super-conducting, recirculating LINAC Energy of up to 155 MeV Operation for external targets, 1 mA, polarized beam Operation in ENERGY RECOVERY MODE (up to 105 MeV) Recirculating with λ/2 phase shift in last return path Deceleration in cavities recovers energy from the beam

⇒ High beam current (up to 10 mA)

Large fraction of the beam can be used for an INTERNAL TARGET ...funded, under construction!

Harald Merkel, Bormio 2016 3/19

Magix - Design Considerations

Using the full power of the MESA beam quality Beam intensity

⇒ High count rate capability (MHz)

Nuclear Physics: Separate energy levels at 100 MeV at 100keV distance

⇒ momentum resolution δp

p < 10−4

Precision measurement of electron scattering cross sections proportional to Mott cross section

dσ dΩ ≈ 1 Q4 ≈ 1 sin4θ/2 ⇒ angular resolution δθ < 0.05◦

Low energetic particles (e, p, below π threshold) Negligible energy loss in window-less gas target Vacuum until first detector layer Excellent position detection in first layer, modest angular detection later

⇒ Focussing spectrometers

Harald Merkel, Bormio 2016 4/19

Magix - Optics

500 1000 1500 2000 2500 z [mm] scale 1:180 x [mm] 500 1000 1500 2000 2500 0.175 0.35 0.525 0.7 B [T]

• 60
• 50
• 40
• 30
• 20
• 10

10 20 30 40 50 60 500 1000 1500 2000 2500 3000 3500

y [mm] path length off central beam [mm]

Harald Merkel, Bormio 2016 5/19

Magix

Harald Merkel, Bormio 2016 6/19

Magix - Targets

• 1. Polarized Target

Polarized Hydrogen target Flow is limited by polarizator (Laser driven/Atomic beam) Luminosities of up to

L = 2×1031s−1cm−2

Polarization

| Pe| ≈ 80%

Polarized Gas Beam T arget cell

• 2. Gas Jet Target

Hypersonic gas jet by Laval nozzle Gas jet caught Expensive part: Pumping system mbar → 10−11 mbar Beam quality: narrow flow delimiters Luminosities of up to

L = 1036s−1cm−2

at 10 mA

Harald Merkel, Bormio 2016 7/19

Physics Program at Magix

Physics Program to employ the strenghtes of MESA and Magix High beam intensity ↔ low target density Excellent beam quality ⇒ Precision physics High degree of beam/target polarization Tuneable to very low energies Selected Examples: Magnetic Radius Tests of ab-initio Calulations in Few-Body Physics Astrophysical S-Factors Search for exotic particles: Search for Dark Photons Invisible Decay of Dark Photons Dark matter beam

Harald Merkel, Bormio 2016 8/19

Magnetic Radius of the Proton

Magnetic Radius from limit Q2 → 0 Suppressed by τ = Q2

4m2

p in cross section

dσ dΩe = dσ dΩe

• Mott

1 ε(1+τ)

• ε G2

E(Q2)+τ G2 M(Q2)

• Beam-Recoil polarization is limited by proton recoil momentum |

pp| > 300 MeV

c

Beam-Target polarization:

A(θ∗,φ∗) = AI sinθ∗cosφ∗ +AS cosθ∗ AI = −2

• τ(1+τ) tan θ

2 GE GM G2

E +

• τ+2τ(1+τ)tan2 θ

2

• G2

M

AS = −2 τ

• 1+τ+(1+τ)2tan2 θ

2 tan θ 2 G2

M

G2

E +

• τ+2τ(1+τ)tan2 θ

2

• G2

M

φ∗ = 0 θ∗ = 0, π

2

• ⇒

A⊥ = Al As ∼ GE GM

Harald Merkel, Bormio 2016 9/19

Magnetic Radius of the Proton - Asymmtry

]

2

/c

2

[GeV

2

Photon Virtuality q

• 0.03
• 0.025
• 0.02
• 0.015
• 0.01
• 0.005

[%] Asymmetry A

• 70
• 60
• 50
• 40
• 30
• 20
• 10

Asymmetry (Calc)

• = 42.0

e

θ Setting

• = 61.8

e

θ Setting

• = 79.3

e

θ Setting

• = 96.9

e

θ Setting

• = 116.2

e

θ Setting

• = 141.8

e

θ Setting = 100 MeV Beam Energy E = 80%

beam

Beam polarization P = 75%

T

Target polarization P Time per setting t = 10d

• 2

cm

• 1

s

31

10 × Luminosity L= 2

(Conservative) assumptions for target ≈ Blast target Statistical error only (systematic error should be small!)

Harald Merkel, Bormio 2016 10/19

Magnetic Radius of the Proton - Errors

— Belushkin (Disp. Analysis 2007) MESA projected error Jones (JLab 2000) Gayou (JLab 2001) Dietrich (MAMI 2001) Pospischil (MAMI 2001) Punjabi (JLab 2005) Jones (JLab 2006) MacLachlan (JLab 2006) Crawford (Bates 2007) Zhan (JLab 2011) – Bernauer (MAMI 2010)

Q2 / (GeV2/c2) µpGp

E/Gp M

10 1 0.1 0.01 1.1 1 0.9 0.8 0.7 0.6

Harald Merkel, Bormio 2016 11/19

Tests of ab-initio Calulations in Few-Body Physics

Ab initio calculations e.g. with Effective Field Theory Consistent chiral expansion of elementary NN-interaction Consistent expansion of Few-Body-Systems Very promising, but

How can we test this?

Harald Merkel, Bormio 2016 12/19

How can we test Ab-Initio-Calculations?

Challenge for theory: Reaction dynamics Possible solution: Use EFT input for potentials Faddeev Calculations for dynamics (J. Golak, H. Witała, ...) Prediction of dynamic observables Promising: Polarization observables Challenge for experiments: Low Momentum Region Needed: High resolution (separate excited states!) Low momentum (use gas targets!) High luminosity (in spite of gas target!) High degrees of beam and target polarization (in spite of high luminosity!)

⇒ Magix @ MESA

Harald Merkel, Bormio 2016 13/19

Astrophysical S-Factor for α(12C,16O)γ

← He-Burning σ ≈ 10−17 barn

How to overcome limits:

• 1. Timereversal (enhancement by factor 10 due to spin weight):

γ+16 O →12 C +α

• 2. Covering the Threshold: Electroproduction in limit Q2 → 0

e+16 O → e′ +12C +α ⇔ γ∗ +16 O →12 C +α

Electron has large momentum, but virtual photon energy goes to zero!

• 3. Detection of slow recoil α ⇒ gas target, recoil detector

Harald Merkel, Bormio 2016 14/19

Search for exotic particles: Dark Photons

γ' Z e− e− Z Z e− e− Z

(a)

(b)

γ'

Dark photon: Force carrier of the Dark Sector Radiative production

e+Z → e+Z +γ ′ → e+ +e−

(detected in Magix)

]

2

[GeV/c

' γ

m

• 2

10

• 1

10

ε

• 4

10

• 3

10

• 2

10

e

(g-2) KLOE 2013 KLOE 2014 WASA HADES PHENIX σ 2 ±

µ

(g-2) favored E774 E141 APEX A1 NA48/2

B A B AR

2009

B A B AR

2014

MESA

Harald Merkel, Bormio 2016 15/19

Beam-Dump Experiments: Motivation

1 10 100 1000 104 1050 1049 1048 1047 1046 1045 1044 1043 1042 1041 1040 1039 1014 1013 1012 1011 1010 109 108 107 106 105 104 103 WIMP Mass GeVc2 WIMPnucleon cross section cm2 WIMPnucleon cross section pb

7Be

Neutrinos

N EU T R IN O C OH E R EN T S CA T TE R ING N E U T R IN O C O HE REN T S C A T T E R IN G

(Green&ovals)&Asymmetric&DM&& (Violet&oval)&Magne7c&DM& (Blue&oval)&Extra&dimensions&& (Red&circle)&SUSY&MSSM& &&&&&MSSM:&Pure&Higgsino&& &&&&&MSSM:&A&funnel& &&&&&MSSM:&BinoEstop&coannihila7on& &&&&&MSSM:&BinoEsquark&coannihila7on& &

8B

Neutrinos A t m

• s

p h e r i c a n d D S N B N e u t r i n

• s

C D M S I I G e ( 2 9 ) X e n

• n

1 ( 2 1 2 )

CRESST CoGeNT (2012) CDMS Si (2013)

E D E L W E I S S ( 2 1 1 )

DAMA

SIMPLE (2012) ZEPLIN-III (2012) C O U P P ( 2 1 2 )

SuperCDMS Soudan Low Threshold SuperCDMS Soudan CDMS-lite XENON 10 S2 (2013) CDMS-II Ge Low Threshold (2011)

SuperCDMS Soudan Xenon1T L Z LUX DarkSide G2 DarkSide 50 DEAP3600 PICO250-CF3I PICO250-C3F8 SNOLAB SuperCDMS

Direct detection experiments: No clear signal yet Limit of sensitivity (solar ν background) will be reached soon Lower masses (i.e. low recoil energy) not accessible

P . Cushman, et al., arXiv:1310.8327

Harald Merkel, Bormio 2016 16/19

Beam-Dump Experiments: Idea

Beam e− Dump 10 m 10 m Dirt Detector χ

Production in beam dump, e.g. via pair production

A0 Z e− e− χ χ

We now have a Dark Matter Beam! Dark Matter particles have enough recoil energy! Detection with simple detector, e.g. scintillator cube ... or with sophisticated DM Detector ...

Harald Merkel, Bormio 2016 17/19

FLUKA Simulation

Neutrons can be shielded Below pion threshold: negligible ν background Clean conditions, detailed layout of hall needed for further design

Harald Merkel, Bormio 2016 18/19

Magix Sensitivity

Reasonable sensitivity for low mass region Multidimensional plot: Assumptions for dark photon mass, mχ

Calculations: G. Krnjaic

Harald Merkel, Bormio 2016 19/19

Summary

MESA: High beam current in Energy Recovery mode Excellent beam quality MAGIX: High Resolution Spectrometers High density or high polarization internal target Multi-purpose setup for precision physics Physics Program Precision form factors: Magnetic Radius of the Proton Nuclear Astrophysics: S-Factor measurements Few-Body physics Search for exotic particles ... Contributions from other groups are welcome!