a short baseline neutrino facility (sblnf) in the cern north area: design overview

A SHORT BASELINE NEUTRINO FACILITY (SBLNF) IN THE CERN NORTH AREA: DESIGN OVERVIEWM. Calviani, I. Efthymiopoulos, A. Ferrari, B. Goddard, R. Losito, J. Osborne, P. Sala, L. Scibile, R. Steerenberg, H. Vincke

8th INTERNATIONAL WORKSHOP ON NEUTRINO BEAMS &

INSTRUMENTATIONNBI2012 – 6th/10th November 2012

M. Calviani et al., Short Baseline neutrino facility (SBLNF) design overview

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Outline

7th November 2012 (NBI2012)

Introduction to the Short Baseline Neutrino Facility Study Group

Experimental requirements Preliminary parameters of the

installation Proto-layout of the installation Neutrino production area configuration Open points and challenges Conclusions


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SBLNF study group


A SBLNF study group has been convened to address the feasibility of a short baseline neutrino facility in the CERN North Area

This should serve primarily the ICARUS/NESSiE experiment (C. Rubbia et al., SPSC-P-347) as well as a neutrino test area for detector R&D and neutrino cross-section measurement

Why not use CNGS? Target area very deep (~60m), too costly to install new

detectors underground DP configuration not adapted for a low energy neutrino

beam

http://cdsweb.cern.ch/record/1432214/files/SPSC-P-347.pdf


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Experimental requirements

Sterile neutrino physics (C. Rubbia et al., SPSC-P-347): Exploring the possible existence of one or more sterile

neutrino Search for spectral differences of electron-like specific

signatures in two identical detectors at two different neutrino decay distances


nm+anti-nm

ne+anti-ne

An exact proportionality between two ne spectra implies absence of neutrino oscillations

1600 m: ICARUS T600 detector + magnetic spectrometer (NESSiE)

350 m: new 150 LAr-TPC detector + magnetic spectrometer (NESSiE)

http://cdsweb.cern.ch/record/1432214/files/SPSC-P-347.pdf


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Preliminary parameters of the installation


100 GeV/c beam momentum Neutrino spectrum peaked at ~2 GeV ND at 350 meters, FD at 1600 meters, middle

position detector at ~700 meters from target DP: length ~80-120 m, radius 100/200 cm

DV of 100 meters is the experiment minimum requirement

Hadron absorber: Graphite core, 2-3 meters long, 1x1 m2 surface Segmented Fe blocks (10/18 meters in total)

Beam line at around 10/15 meters from “ground”


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CERN accelerator complex


SBLN

F


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Primary beam configuration


100 GeV/c baseline primary beam momentum 3.5*1013 p/pulse (4.5*1013 p/pulse ultimate

running) 6s (3.6s min) repetition rate ~100 kW (200 kW) beam power Time sharing between fixed-target physics

Yearly POTs between ~3-4.5*1019 p+/yr New extraction lines from existing tunnels Beam 1s on target: 1-2.5 mm, divergence ≤1

mrad


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Beam extraction from SPS


Magnetic septa

(MST+MSE)

Short baseline neutrino beam

Beam excitation via injection kicker in LSS1 + extraction via existing septa

Solution tested for low intensities during recent beam tests

B. Goddard

Fast extraction not available in the SPS North Area branch (complex to install a new kicker in a short time)

Injection kicker (MKP)

slow


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Beam line ~parallel to the existing North Area lines

New production infrastructure

Experiments and neutrino beam test areas

Target area

Near detector~350 meters

Testing area for new generation detectors

Far detector~1.6 km


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Muon fluence and constraints


Decay pipe

Hadr

on st

oppe

r

Moraine soil

Proton momentum

Muon range (from target)

100 GeV/c ~320 meters



Assumptions: 4.5*1013 p/pulse 1.9 g/cm3 moraine density DP 100 m long HS: 3 m core + 7 m Fe

ND should be at least at 350 meter from target!


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Neutrino beam production area configuration


The baseline configuration of the target area inspired by both AP0/NuMI “chase” and T2K: No direct personnel access close to production

elements Reduced number of equipment in hot zones Remote maintenance on all equipment Reduced air volume around the production elements Allow for target volume and decay pipe under He

environment (TS and DP separated in case of access) Shallow depth calls for heavy shielding around target

trench and decay pipe


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(Proto) layout of the installation (FLUKA)


Ground (moraine)

Decay pipeDecay pipe shielding

Hadron stopperTarget station building and

vault

Primary beam area

Target chase

Target shielding

FLUKA preliminary implementation:Shielding thickness not optimized!


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(Proto) layout of the installation (FLUKA)


Ground (moraine)

Target chase

He vessel (medium blue)

Concrete shielding (red)

Iron shielding (dark blue)

Target station building and vault

Target & horn/reflector

300

cm20

0 cm

300 cm


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Absorber/m stations


Hadron absorber: Effective iron length of 10/18

meters Water cooling system (surface)

Muon pits (i.e., diamond-detectors): Pit 1 inside the dump to be sensitive

to low energy m (~5 GeV) Pit 2 downstream the absorber Access via a dedicated surface building


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Potential target configuration


CNGS target design Cooling by radiative

emission and partly by convective exchange

Graphite at high temperature (~1000 °C)

Revolver structure would have allowed to exchange remotely target without interventions


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SBLNF: CNGS-like “evolutionary” design graphite/beryllium options under investigation Simpler construction and more diagnostics Complete remote manipulation Possibility to have a closed He-loop cooling

(enhanced convection) – external air blow could be avoided Pressurized circuit with an external heat exchanger

No segmentation required by physics Larger rod and beam radius (~4-10 mm radius)

Reduced off-axis vibration issues Enhanced production of low energy p/K PRELIMINARY

DESIGN ON-

GOING


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Advantages DisadvantagesTarget inside horn

Higher pion collection from target

More difficult maintenance and construction

Less degree of freedom for target design

Electrical coupling between target/horn

Target outside horn

Easier maintenance and installation

More degree of freedom for a more robust design

Less efficient in pion collection

For both solution the baseline is to have a passive or actively He-cooled target

PROS & CONS

TO BE STUDIED

IN DETAIL


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Preliminary radioprotection aspects


Optimisation: annual dose <100 mSv for exposed personnel (<10 mSv for general public)

CERN dose limits: 6 mSv/y or 20 mSv/y (for radiation workers), 1 mSv for other

personnel working at CERN and 0.3 mSv/y for general public

Detailed studies to follow: Required shielding (thickness, material choice) Induced radioactivity (structure, surroundings, soil, groundwater) Optimization of design to minimize intervention doses for

maintenance personnel Waste & decommissioning


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Preliminary radioprotection aspects


H*(10) with the current shielding: In the target vault <10 mSv/h Above DP, At 15 m from beam axis

< 1 mSv/h Values manageable with a proper

shielding design

PRELIMINARY


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Challenges in the design


He vessel for TS/DP: Material/thickness? He at atmospheric pressure? Closed loop with recirculation? Purge system? Constraints in He purity for a C/Be target? Which shielding elements should be included in the

vessel? Separate volume via appropriate shutter (closed

during access) to avoid purging the DP volume

Several technical questions concerning the engineering of the installation are still open


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Challenges in the design


Target: In case of a He-cooled target, shall we keep the target

and He-vessel circuits separated? How critical is the purity in the He-loop?

Shielding: Inner iron layer water/air cooled (~50 kW deposited)? Decay pipe inner layer shall be water cooled (T2K-like?)

Soil/water activation minimization: Groundwater mobility for surface layers? Careful design of the interface between activation zone

and surrounding earth Radioactive gas emission in the TS


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Conclusions


A study group has started addressing the technical feasibility of a short baseline neutrino facility in the CERN North Area

It would be a 100 GeV/c p+ beam, ~200 kW installation, at shallow depth (10/15 m)

Neutrino production area to be a “chase”-based design

Significant design efforts to be dedicated in 2013 to have it operational in the next few years

Design experience from NBI colleagues will be precious, considering feedback from running

installations (T2K/NuMI/NoVA)

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Backup



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(Proto) layout of the installation


Main target vault, housing: Target/horn/reflector

trench Radioactive storage

area A temporary shielded

area - fast inspection and “easy” repair

Annex service building: general services and

assembly


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Open points: TS energy deposition

Target: ~1.5 kW “Chase” iron shielding:

~50 kW deposited power

Air/He cooling necessary?

DP shielding: ~68 kW on the first 50

cm layer thermal cracking?

Mitigation strategy to be further investigated

Region kJ/pulse kW (average)Target 5.62 1.56Top Fe shielding (layer 1) 48.32 13.42Lateral Fe shielding 57.50 15.97Bottom Fe shielding 55.42 15.39Decay pipe shielding (total) 258.56 71.82Hadron stopper (graphite) 159.54 44.32Hadron stopper (iron) 123.70 34.36Horn (total) 7.01 1.95Reflector (total) 5.05 1.40



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Layout considerations


The position of the target is constrained by: Existing buildings Bending radius of

the extraction line The near detector

distance from target and existing buildings

a short baseline neutrino facility (sblnf) in the cern north area: design overview

Documents

neutrino test area

low energy neutrino

design overviewm

target area

detector rd

middle position detector

cern north areathis

identical detectors