Status and prospects of the NEXT experiment J.J. Gmez Cadenas on - - PowerPoint PPT Presentation

Status and prospects of the NEXT experiment

J.J. Gómez Cadenas on behalf of the NEXT collaboration

Donostia International Physics Center (DIPC)

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 1 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 2 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 3 / 40

Majorana’s challenge

Today: T 0ν

1/2 ∼ 1026yr.

“Good luck case”: if T 0ν

1/2 ∼ 1027yr, observe 3 signal events (per ton and year) for

mββ ∼ 15 meV. “Tough luck case”: if T 0ν

1/2 ∼ 1028yr, observe 0.5 signal events (per ton and year) for

mββ ∼ 15 meV. Bottom line: To explore IO exposures in the range of ton (tens of ton) year needed and virtually background free detectors.

• A. Giuliani, Neutrino 2018

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 4 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 5 / 40

What is NEXT?

A HPXe: High pressure gas chamber (10-20 bar) with EL amplification of the signal. Uses xenon, a noble gas (source=detector) with relatively high Qββ and no long-lived radioactive isotopes. An optical TPC: all signals are light. Primary scintillation (S1) gives t0 (needed to fiducialize the event and to correct for finite electron lifetime), EL amplification gives S2, which is used to measure energy and to reconstruct the electron trajectory.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 6 / 40

NEXT assets

Topological signal, capable to separate signal “double electrons”, from backgrounds “single electrons”. Excellent energy resolution, 20 keV at Qββ. Possibility to identify Ba++ produced in 136Xe → Ba++ + 2e(+2ν), through SMFI.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 7 / 40

The NEXT program

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 8 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 9 / 40

NEXT White (NEW)

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 10 / 40

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 11 / 40

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 12 / 40

Goals of NEW

Demonstrate technology is robust. Demonstrate energy resolution and topological signature. Measure backgrounds to establish a reliable background model (and to improve it as needed).

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 13 / 40

Operation of NEW

Taking data since 2016. Very stable operation since 2017. Less than 1 gram of gas lost per year. Very high lifetime, measured on a daily basis with Krypton calibrations.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 14 / 40

NEW energy resolution

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 15 / 40

NEW topological signature

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 16 / 40

Blob analysis, in 208Tl double escape peak shows good agreement data/MC. DNN analysis, optimizes separation signal/background. Shown MC prediction: 90 % signal efficiency 10% background contamination.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 17 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 18 / 40

Background measurements (Run IV, 2018)

Figure: Fiducial background rate for Run IV (2018) as a function of data taking calendar day. Vertical dashed lines mark the times where Run-IVa, Run-IVb and Run-IVc started.

Run IVa. No radon free air, no inner shielding. Run IVb. Radon free air. Run IVc. Radon free air and inner shielding

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 19 / 40

Background composition

Figure: Contribution of the dominant background isotopes to NEXT-White radioactive budget.

Notice, only 214Bi and 208Tl relevant for ββ0ν searches.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 20 / 40

Run V (enriched xenon)

Figure: We really have enriched xenon...

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 21 / 40

Measurement of ββ2ν mode (Run V)

Figure: Energy spectra, Run V.

Notice, Run V just started (15 days taking data with enriched xenon). Will run until the end of the year to provide a measurement of ββ2ν lifetime.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 22 / 40

High energy spectrum with topological cuts

Figure: Energy spectra with topological cuts data and MC.

Topological cut cleans high energy region where signal is expected (notice the hole). One candidate event found in the data by basic topological analysis (visual inspection shows badly reconstructed single electron event).

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 23 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 24 / 40

NEXT-100

Scales up NEXT-White by roughly 2:1 in dimensions. Currently in construction. Commissioning in 2020.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 25 / 40

Next-100 radioactive budget

Expected background rate, 4 × 10−4counts/(keV · kg · y). Expected background, 1 event per year in ROI. Dominant source PMTs.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 26 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 27 / 40

NEXT2-HD

Symmetric TPC: Diameter 2 m, drift length 3 m, pressure 20 bar, 1 ton per module. Uses only SiPMs mounted in ultra-pure substrates (gas cooled to -60 C). Low diffusion mixtures (Xe-He, Xe-CH4).

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 28 / 40

NEXT2-HD improves rejection factor of topological signature

Sharper topology results in an improvements of rejection factor by a factor 3. Energy resolution may be further improved yielding a factor 2 (214Bi peak very close to Qββ).

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 29 / 40

NEXT2-HD: incremental improvement approach

SiPMs mounted in ultra-low background substrates, ultra-pure copper for inner shield, minimize materials inside TPC, deep underground location, water tank with neutron veto... an order of magnitude reduction in radioactive budget may be possible. Combination with improved topological signature and improved energy resolution may result in a “background free” detector at ton scale.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 30 / 40

NEXT2-BOLD

If the Ba++ produced in the 136Xe → Ba++ + 2e(+2ν) can be detected efficiently,

• ne could aim for the BOLD (Barium iOn Light Detection) option.

Detecting “tagging” the Ba++ signaling a ββ0ν process has been a long sought holy grail of xenon chambers. Dave Nygren’s proposal to do it using SMFI (Single Molecule Fluorescence Imaging) could turn fantasy into reality.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 31 / 40

A bright idea

Dave Nygren’s, 2016: https://www.symmetrymagazine.org/article/a-bright-idea

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 32 / 40

Single Molecule Fluorescence Imaging

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 33 / 40

SMFI with Ba++. Proof of concept

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 34 / 40

SMFI setup

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 35 / 40

We see single molecules chelated with Ba++!

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 36 / 40

Next step? RITA

RadIum TAgging (RITA) in dry medium (we can use several noble gases at different pressures). Ra++ produced by TH-228 decays. Radium and Barium are chemical "twin brothers" (same ionization potential, same radius, etc.). We can tag the production of Ra++ ions counting the recoiling alphas. Target will be a mon-layer of suitable molecules capable to capture the ion in gas and produce a strong fluorescence. If RITA succeeds we may have a serious case for a BOLD NEXT-2.0 detector.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 37 / 40

Table of Contents

1

Desperately seeking Majorana

2

Neutrino Experiment with a Xenon TPC (NEXT)

3

NEXT White (NEW)

4

Background measurement in NEXT-White

5

NEXT-100

6

NEXT-2.0

7

Summary and outlook

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 38 / 40

Summary and outlook

After successful operation of the NEXT-White demonstrator we expect to commission NEXT-100 in 2020. We intend to operate NEXT-100 for about one year, to measure our background index and then upgrade the detector to a “high-definition” version, while we keep working in our SMFI barium tagging program. Thus we intend to keep open our

• ption for an “incremental" (HD) or “disruptive” (BOLD) NEXT-2.0 detector(s)

aiming for exposures in the tens of ton year and extremely low backgrounds needed to maximize the chances of a discovery.

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 39 / 40

The NEXT collaboration

J.J. Gómez Cadenas on behalf of the NEXT collaboration (Donostia International Physics Center (DIPC)) Status and prospects of the NEXT experiment March, 19, 2019 40 / 40