SBLNF: update on secondary beam line SBLNF meeting 12 th November 2012

SBLNF: update on secondary beam line

SBLNF meeting 12th November 2012

M. Calviani, A. Ferrari, R. Losito, P. Sala, Hei. Vincke

2 M. Calviani, SBLNF meeting

Outline

1. Updates on the m pits2. Prompt dose rate due m downstream the

dump3. Target design possibilities4. Updates on the general target station design5. RP aspects pit and He-vessel (to be treated

in a separate presentation)

12th November 2012


Updates on the m pit

12th November 2012

Pit1 = 3 m C + 2 m Fe Pit2 = Pit1 + 10 m Fe


Updates on the m pit

Building on top of the m pits necessary for: Access to the two m pits (concrete shielding) Location of the hadron absorber cooling station Location of a potential DP water cooling station (if

needed!) Building will need shielding if the absorber

cooling station will be located there Total dose on the 1st pit ~1 MGy/y

Potentially no human access since first beam Diamond-detector the only option?

12th November 2012


m pits – m spectrum

12th November 2012

“thermalized” m spectrum in both pits We don’t know

from which p these m come from!

Shape remains the same as a function of depth shift the HE part

towards lower energies

For increasing depths


m pits – m parents spectrum

Energy distribution of parents p/K generating m which arrive in the pit1 and pit2

12th November 2012

pit1 pit2~4.

6±0.

5 G

eV >16 GeV

> 3 GeV


m pits – sensitivity to misalignment

Sensitivity to proton steering on target

Primary beam 2 mm of target: ~5 cm off-

centre @pit1 ~35 cm off-

centre @pit2

12th November 2012

~35 cm

~5 cm

PRELIMINARY


m pits – sensitivity to misalignment

Effect on horn/reflector 8 mrad misalignment

12th November 2012

Target/horn tilted by 8mrad (0.5 deg) Reflector tilted by 8mrad (0.5 deg)

PREL

IMIN

ARY

PREL

IMIN

ARY

Pit1 very sensitive!

~40 cm, deformed spectrum

~40 cm

Pit2 sensitive only to very high energy m!


m pits – preliminary conclusions

The foreseen location of the pits are well adapted to sample the neutrino energy of interest Pit1: 2 meters after C core Pit2: 10 meters Fe after Pit1

Important to have at least two pits:1. Alignment (longer arm lever)2. Monitoring of target health (NuMI experience

with failing targets)3. Potential use of m flux for n flux prediction

(normalization)

12th November 2012


H*(10) downstream absorber

The hadron absorber significantly reduces the prompt dose rate downstream and lateral

Still a significant amount of m are present around – contributing to the prompt radiation levels

12th November 2012

Lateral view Top view


H*(10) downstream absorber (vertical view)

12th November 2012

Beam

axi

s

~5 mSv/h

Z = [120-135] m

H*(10) averaged 15 meters downstream the absorber

~5 mSv/h are reached ~8 meters from beam axis

PRELIMINARY


Potential target configuration

3 configurations presently being investigated: “stand-alone” graphite target – CNGS-inspired T2K-like target (inside horn) Air/He-cooled beryllium target

For the moment being investigated in parallel Material choices limited to graphite &

beryllium Energy deposited in the target ~2 kW (for

~240 kW beam power)

12th November 2012


Target inside horn

12th November 2012

Magnetic field

Thickness minimum possible to maximize magnetic field inside horn

Proton beam


Target outside horn:

12th November 2012

Magnetic field

Proton beam


Potential target configuration

12th November 2012

For both solution the present conceptual design is to have a passive or actively He-cooled target

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

Max target temperature limited by horn inner conductor

Target outside horn

Easier maintenance and installation

More degree of freedom for a more robust design

Less efficient in pion collection


Optimisation of target size

12th November 2012


Solution #1 Target outside horn:

Graphite target, He-flow active cooling (closed loop) Passive cooling (CNGS) should be excluded due to the high

air flow required to cool the external tank High temperature graphite advantageous for material

properties (reduction of radiation damage) Structural support can be a CNGS-similar configuration Design possible only if outside horn

12th November 2012

heliumProton beam

He inlet He outlet

Lateral view

He inlet He outlet


Solution #2 Target inside/outside horn:

T2K approach (graphite target, high temperature)

Closed-loop Cantilever design He-cooled target (requirement of O2<100 ppm)

12th November 2012

heliumProton beam


Solution #3 Target inside horn:

Graphite/beryllium (low temperature – horn internal conductor)

He cooling Cantilever design MiniBooNE-inspired design (open loop)

Beryllium rod and cooling fins (extruded from a bigger block) “Open” circuit design possible

12th November 2012

Proton beam

Extra

ctio

n +

purifi

catio

n lo

op?

Lateral view Front view

helium


Energy deposition in target

12th November 2012

4 mm radius targetsbeam = 1 mm

10 mm radius targetsbeam = 2.7 mm

Graphite case (1.8 g/cm3) Similar values for beryllium

Max ~400 J/cm3/pulse Max ~100 J/cm3/pulse


Temperature increase per shot

Graphite and Beryllium, in the “big-target” configuration DTmaxC = ~80 °C/pulse (~250 °C/pulse for “small”) DTmaxBe = ~50 °C/pulse (~135 °C/pulse for “small”)

12th November 2012

graphite beryllium


Energy deposition for “small” target

12th November 2012

Graphite: DTmax~250 °C, 9 MPa compressive stress (~60 MPa max)

Beryllium: DTmax~140 °C, 450 MPa compressive stress (~250 MPa

max) Beryllium small target excluded!

graphite beryllium

A. Perillo-Marcone


Hadron absorber A CNGS-like approach might be followed for the SBLNF Graphite core (water cooled) surrounded by Fe

shielding 45 kW deposited in the graphite (primary beam ~10 cm Ø) 35 kW deposited in Fe

Part of the absorber embedded in the He-vessel Top Fe needed for m prompt dose rate reduction!

12th November 2012

Graphite FeAl water cooling

Al water cooling

Primary beam/hadrons


Roadmap Collaboration with experiments to address the

target position (in/out horn) Detailed thermo mechanical assessment of target

and absorber has started Graphite and beryllium analysis will proceed in parallel

Follow-ups on: Requirements for DP cooling! Requirements for cooling of target chase shielding

elements! Requirements for the target collimator (size/max thermal

load) Objective is to narrow down the main needs

in the next few weeks12th November 2012


Conceptual design for TS buildings

12th November 2012


Updates on the target station

design He-vessel: Vessel need to be thick enough

to allow evacuation before accessing the target – T2K are (5)10 cm steel plates

Water or air cooling needed (to be studied)

Avoid concrete shielding in the vessel to avoid 3H production

Dehumidification to be thought from the very beginning (reduce HTO in air)

Fe shielding blocks (top+lateral) in the vessel (desorption of 3H)

12th November 2012

Fe Fe

Fe

Fe

Fe Fe

Fe

Concrete

He vessel layer Not in scale

28 M. Calviani, SBLNF meeting 12th November 2012

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


Conclusions

12th November 2012

m pits well optimized for a low energy neutrino beam

He-vessel adopted as baseline for reduction of air activation

Shielding and cooling needs in the target chase will be analysed taking into account thermo mechanical and RP aspects (water activation)

Few selected target configurations have been considered for more detailed thermo mechanical analyses

SBLNF: update on secondary beam line SBLNF meeting 12 th November 2012

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