CNGS - CERN Neutrinos to Gran Sasso

29 June 2006CERN Neutrinos to Gran Sasso

Seminar for CERN guides, by K. Elsener 1

CNGS - CERN Neutrinos to Gran Sasso

> “Neutrinos” and “Gran Sasso”

> CNGS Schedule

> Main components, installation at CERN

> Neutrinos at CNGS (some numbers)



A sincere “ THANK YOU ! “

to the many colleagues who are contributing,at CERN and elsewhere, to the CNGS project



What are Neutrinos () ?

elementary particles

come in three flavors (LEP) (pistachio, chocolate, vanilla)

electric charge: zero !mass: very small zero? interaction with matter:

“very weak”

“ the elusive particle “

Leptons electric particle charge

e -1

e 0 ------------------------------------

-1

0-------------------------------------

-1

0

+ a

ntip

article

s



Where are the Neutrinos ?

“all around us” -> radioactive decay of atomic nuclei (natural)

n --> p + e + e

every person is a neutrino – emitter: 340 millions per day20 milligrams radioactive potassium (40K)




-> from nuclear reactors -> from the sun

4x1014 neutrinos per second from the sunare traversing our body, but ...

...in 100 years, only 1 solar neutrino interacts with our body.

One would need an iron block 1016 meters long in order to “stop” 50% of the solar neutrinos



-> at accelerators… (high energy neutrinos)

(proton + Nucleus -> pions -> decay)


-> from collisions of cosmic rays with nuclei in the atmosphere

-> everywhere around us (cosmic ...)

... ...



How do we detect neutrinos ?

e

e

p,n,,K...

p,n,,K...

p,n,,K...

neutrinos interact VERY rarely with matter - when they do,they often produce a lepton of their “own flavour”:

NOTE: a minimum amount of energy is needed (to create the mass of the lepton):

me = 0.5 MeV, - m = 106 MeV - m = 1770 MeV

The higher the neutrino energy, the more likely the interaction !



Neutrino mass ?

Standard model of particle physics: masses “ZERO”

“Direct” mass measurements -> upper limits( in decay experiments measuring kinetic energy of “the partner” )

me < 2.2 eV m

< 170 keV m < 15.5

MeV

What’s the problem ? OBSERVATION 1 : SOLAR NEUTRINO “DEFICIT”

only about 50% of the e expected are actually observed: e

disappear “en route” from the sun to the earth …



OBSERVATION 2 : “ATMOSPHERIC NEUTRINO ANOMALY”

much less “from below”observed w.r.t. expectations

disappear “en route” over 10’000 km … ?



Neutrino Oscillation

’s change flavor ! Is this possible? --> Yes, “if neutrinos have mass”!

Gran Sasso

e



In Dec. 1999, CERN council approved the CNGS project:

build an intense beam at CERN-SPS

search for appearance at Gran Sasso laboratory (730 km from CERN)

“long base-line” -- oscillation experiment

note: K2K (Japan) completed; NuMI/MINOS (US) running





ORGANISATION of CNGS

CERN INFNConvention

builds and operatesCNGS neutrino beam

operates the Gran Sassounderground Laboratory,which houses detectors

International

Collaborations

bilateral co-ordinationcommittee

CERN and LNGSscientific committees

special contributionsfinance a large fraction of CNGS



The Gran Sasso Laboratory(LNGS)



730 km might seem too short -but look at the details :Background low enough,event rate still acceptable--> 730 km almost perfectAND, VERY IMPORTANT:

- existing laboratory with its infrastructure (since 1987)- large halls directed to CERN- caverns in the GS mountains: 1500 m of rock shielding- tradition in very successful neutrino physics experiments (solar ’s)



e

,e,

p,n,,K...

Detecting at Gran Sasso

-> look for the lepton:extremely difficult -

travels less than 1 mm before decaying

-> two approaches: (a) very good position resolution (see the decay “kink”) -> OPERA (b) very good energy and angle resolution -> ICARUS



decay “kink”

~ 0.6 mm

Neutrinos

Electron(or muon)

Hadrons

A tau event can be identifiedbecause it leaves several tracks starting at the same « point » (the neutrino interaction vertex) – one of the tracks (the tau) shows a kink after about ~1 mm.

A detector with excellent spatial resolution is required !

1 mm



massive « target » : lead platesmicrometric precision : emulsions

assembled in small units called bricks modular detector rapid analysis

56 lead plates (1 mm thick) alternating with56 photographic films (emulsions).

8.3kg

10.2 x 12.7 x 7.5 cm

Brique

Brick

Pb

Couche de gélatine photographique 40 m

1 mm



OPERA: 1800 tons of “detector mass”walls made of bricks (total more than 200’000)

-> bricks made of “sandwiches”-> sandwiches made of lead and nuclear emulsion

(type of film)

artists view (2001)



artists view (2004)



Target SM1

SM1 SM2

Aimants

OPERA status, November 2005



p + C (interactions) , K (decay in flight)

CNGS beam-line: the main components (1)

(based on CERN experience: PS / SPS neutrino beams -> WANF)

“back to CERN”...



p + C (interactions) , K (decay in flight)

CNGS: the main components (2)

vacuum

700 m 100 m 1000m 67 m







CNGS schedule



CNGS works

ground breaking ceremony: 12 October 2000



CNGS civil engineering

more than 3 km of tunnels and caverns (diameter 3.1 m -> 6.0 m)

more than 45’000 m3 rockto be removed

more than 12’000 m3 concreteto be “sprayed” or poured



CNGS -- proton beam

-> protons from SPS, 400 GeV-> NEW fast extraction - tested in 2004

-> this extraction system needed for TI8 -> LHC transfer line (but modified for CNGS)

-> CNGS p-beam branches off after 100 metres

-> 700 metres of proton beam line to CNGS target (proton beam spot: = 0.5 mm)



Electrical distribution

box

Beam position monitor control electronics

MagnetInterlockelectronics

Dipole corrector

Quadrupole

5.6% slope

BEAM

BEAM

CNGS -- proton beam

typical “half cell”

73 deflection (dipole) magnets (6.4 m long, 11 tons) +21 quadrupole magnets + correction dipoles + ...



Proton beam tunnel – February 2002



Proton beam tunnel – April 2003



Proton beam tunnel – Dec. 2004



Proton beam tunnel – Feb. 2005



Proton beam tunnel – 1 July 2005



Proton beam tunnel – 13 July 2005



Proton beam – November 2005


Seminar for CERN guides, by K. Elsener 39Proton beam: Monitoring equipment and vacuum system

beam position

beam profile

ion pump


Seminar for CERN guides, by K. Elsener 40Proton beam: Final focusing towards the target


Seminar for CERN guides, by K. Elsener 41Proton beam: last beam position / beam profile monitors upstream of the target station collimator and shielding



-> 10 cm long graphite rods, Ø = 5mm and/or 4mm

CNGS -- target

protonbeam

Note: - target rods thin / interspaced to “let the pions out”

- target rods need to be precisely aligned (0.1 mm)

- target needs to be cooled (particle energy deposition)





target unit (assembly of Alu container)



target magazine (4 spare target units)


Seminar for CERN guides, by K. Elsener 46Target station installed in final configuration – 8 March 2006



target magazine with motors, in the lab



target station motor / indexing finger



CNGS -- focusing devices

length: 6.5 mdiameter: 70 cmweight: 1500 kg

Pulsed devices:150kA / 180 kA, 7 ms

water-cooled:distributed nozzles



“Magnetic Horn” (S. van der Meer, CERN 1961)



0.35 m

35 GeV positively charged particles leaving the target

Principle of focusing with a Magnetic Hornmagnetic volume given by “one turn” at high current:

specially shaped inner conductor - end plates cylindrical outer conductor

inner conductor



secondary beam focusing with horn/reflector



CNGS -- focusing devicesDesign criteria:>95% probability to work for 20 Mio. pulses

courtesy LAL/IN2P3



The inner conductor:- as thin as possible (particle absorption)- as thick as necessary (mechanical stability)

courtesy LAL/IN2P3



reflector assembly – inner and first “barrel” of outer conductor



reflector assembly – inner and second “barrel” of outer conductor



reflector assembly – connection plate with GRAFOIL ring and glass disk



reflector assembly – connection plates onto first “barrel”



magnetic horn completed (in the laboratory)


Seminar for CERN guides, by K. Elsener 60horn in the lab – beam entrance side


Seminar for CERN guides, by K. Elsener 61horn in the lab – beam exit side (“neck”)



reflector transport – arrival at BA4


Seminar for CERN guides, by K. Elsener 63reflector transport – in the service gallery


Seminar for CERN guides, by K. Elsener 64horn installation in the target chamber – 31 Jan. 2006



Powering of a Magnetic Horn6000 V / 9000 A

400 V / 150000 A

”Stripline”



“stripline”150000 A



3 twistedcables6000 V /9000 A


Seminar for CERN guides, by K. Elsener 68in progress: horn roof closure



horn roof shieldingcompleted



Helium Tank and shielding



/ K profile at entrance to decay tunnel



CNGS -- decay tube

- dimensions of decay tube: 2.45 m diameter steel tubes, 6 m long pieces, 1 km length welded together in-situ vacuum: ~1 mbar tube embedded in concrete


Seminar for CERN guides, by K. Elsener 73decay tube sleeves produced and delivered “just in time”



6 m long sectionlowered down theCE shaft


Seminar for CERN guides, by K. Elsener 756m long tube transported along the access gallery



target chamber: assembling the 18m long sections


Seminar for CERN guides, by K. Elsener 7718m section transported along the decay tunnel



Welding inside decay tube



CNGS -- hadron stop

- hadron stop: 3.2 m graphite 15 m iron blocks

upstream end: water cooled



11 July 2003 – near the shaft PGCN

graphite

cooling modules




Seminar for CERN guides, by K. Elsener 82Hadron stop – 28 July 2003


Seminar for CERN guides, by K. Elsener 83Hadron stop – 2 Sept. 2003



CNGS -- muon detectors



expected CNGS muon profiles

first muon chamber second muon chamber



muon detectors(ionisation chambers)





Radial distribution of the- beam at Gran Sasso

detector cross section



Neutrinos at CNGS – some numbers:

For 1 day of CNGS operation, we expect:

protons on target 2 x 1017

pions / kaons at entrance to decay tunnel 3 x 1017

in direction of Gran Sasso 1017

in 100 m2 at Gran Sasso 3 x 1012

events per day in OPERA 25 per day

events (from oscillation) 2 per year





more information:

www.cern.ch/cngs

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CNGS - CERN Neutrinos to Gran Sasso