W. Scandale 1

Status of UA9

Walter Scandale CERN

CC095th workshop on crystal channeling

24-27 March 2009

W. Scandale 2

Outlook

The crystal collimation concept

Lessons from H8RD22

The UA9 layout

What is already installed.

Plans

Conclusions

W. Scandale 3

Two stage collimationin a circular collider

Secondary halop

pe

Pri

mary

co

llim

ato

r(s

catt

ere

r)Beam CoreBeam Core

Shower

Primary Primary halo (p)halo (p)

Secondary collimator(massive absorber)

€

capture condition :

δx' >N2

2 −N12

( ) εN

γ βTWISS,

with εN = εβγ .

<x’2>~ L

How it works ? Short scatterer deflects the primary halo

(ap. r1=N1√βTWISSε)

Long collimator intercepts the secondary halo (ap. r2=N2√βTWISSε)

halo particles captured through amplitude increase via multiple scattering and multi-turn effect.

r1 r2

W. Scandale 4

p

Beam propagation

Primary Primary halo (p)halo (p)

Absorber

Coherent deviation of the primary halo Coherent deviation of the primary halo

Larger collimation efficiencyLarger collimation efficiency

Reduced tertiary haloReduced tertiary halo

Crystal

Crystal collimation

Beam CoreBeam Core

E. Tsyganov & A. Taratin (1991)

W. Scandale 5

Particle-crystal interaction

d

UVolume reflection Prediction in 1985-’87 byA.M.Taratin and S.A.Vorobiev,

First observation 2006 (IHEP - PNPI - CERN)

Possible processes: multiple scattering channeling volume capture de-channeling volume reflection

W. Scandale 6Rotation angle (µrad)

An

gu

lar

pro

file

(µ

rad

)

1 - “amorphous” orientation

2 - channeling (50 %)

3 - de-channeling (1 %)

4 - volume capture (2 %)

5 - volume reflection(98 %)

Angular beam profileas a function

of the crystal orientation

1 1

34

2

5

The particle density decreases from red to blue

The angular profile is the change of beam direction induced by the crystalThe rotation angle is the angle of the crystal respect to beam direction

9mm long Si-crystal deflecting 400GeV protons

(peak efficiency)

W. Scandale et al. PRL 98, 154801 (2007)

TAL

UA9The underground experiment in the SPS

Approved by the CERN Research Board of the 3 Sept 2008

CERN

INFN

PNPI

IHEP

JINR

SLAC

FNAL

LBNL

Goals: Demonstrate loss localization Measure channeling and collimation

efficiency Measure the single particle dynamics

(later ?)

UA9 layout

tankIHEP tank

RP1 RP2TAL (tungsten)600x30x30 mm3

Installed

Installed

RD22 tank

RD22 tank

RD22 goniometer

RD22 tank with goniometers and thin target

crystals

Crystal alignment table

Layout of the RD22 tank

Beam axisS

ingle

str

ip c

ryst

al

Quasi

mosa

iccr

yst

al

Hori

z.sc

raper

1m

m W

30

x3

0 m

m2

Quart

zC

ere

nco

vdete

ctor

Laser table for crystal alignment

Mult

iC

ryst

al

cable

s

Mult

iC

ryst

al

cable

s

Mult

iC

ryst

al

cable

s

GEM

GEM

Sci

nti

llati

ng

counte

r

Sci

nti

llati

ng

counte

r

TAL (secondary collimator)

TAL (secondary collimator)

RP1 (the CERN roman pot)

RP1 (the CERN roman pot)

RP2

Beam loss and scintillator counters

C1 C2

C3

C4

BLM

BLM

BLM BLM

The SPS beam

• We selected two energies of interest: – 120 GeV, as for the RD22 experiments (reference data in the

literature);

– 270 GeV, as for other planned experiment in the SPS (faster setting-up)

High energy unbunched bunched

RF Voltage [MV] 1.5 0 1.5

Momentum P [GeV/c] 270 120 120

Tune Qx 26.13 26.13 26.13

Tune Qy 26.18 26.18 26.18

Tune Qs 0.0021 0 0.004

normalized emittance (at 1 ) [mm mrad]

1.5 1.5 1.5

transverse radius (RMS) [mm] 0.67 1 1

momentum spread (RMS) p/p 2 to 310-4 2 to 310-4 410-4

Longitudinal emittance [eV-s] 0.4 0.4 0.4alternative tunes are those selected in RD22 (Qx=26.62, Qy=26.58).

The SPS beam

• Intensity a few 1011 up to a few 1012 circulating particles.

• Beam either unbunched or bunched in a few tens of bunches.

• Beam lifetime larger than 80 h, determined by the SPS vacuum.

• A halo flux of a few 102 to a few 104 particles per turn, which can be investigated with the detectors in the roman pots

• evenly distributed along the revolution period (unbunched beam);

• or synchronous to the bunch structure (bunched beam).

• Larger fluxes up to a few 105 particles per turn, which should be studied using only the beam loss monitors.

Beam footprint in the crystal

QF518 QF520QD519

taratin

Deflected beam

Particle trajectory with α=150 μrad

Expected efficiency for α=150 rad

amorphous orientation

Optimal orientation for channeling

VR (-)

position angle

TAL hit

Probability to hit the TAL and RP2

Probability to hit the TAL

Probability to hit the TAL, PR1 and RP2

Plans for 2009

UA9• First run: June 09• Loss localization experiment by Sept 09• Efficiency measurement by Nov 09

W. Scandale 26

Conclusion

Infrastructure ready (cables, mechanics, beam loss monitors, RF noise, Beam intensity monitors)

Basic hardware installed (Tank, two gonioneters, two crystals, TAL)

Detectors in progress

Already installed: 1 cerencov

To be installed this week: 6 scintillators, 3 GEM, 1 si-strip, 3 BLM

To be installed possibly in May: 1 cerencov, 2 scintillators, a fibrometer, more si-strip

UA9 ready to start crystal collimation tests in June 09