PANDA collaboration Dubna 04072007

Moscow-Jülich Pellet Target: 

Moscow-Jülich Pellet Target … a brief status report

INTAS project: 

INTAS project “Development of a Pellet Target for PANDA” (INTAS 06-1000012-8787, 2007/08) Consortium: FZJ: Coordination, Beam-target interactions, pellet generator GSI: Interfacing to PANDA UU: Real-time pellet tracking ITEP, MPEI: Pellet generator, simulations Technical drawings: end of 2008 Construction 2009+

How to produce frozen pellets: 

How to produce frozen pellets Triple point chamber: Liquid jet splits into droplets Beam (accelerator, laser, …) Transition (“sluice”) Vacuum Flux of frozen pellets

Breakup of fluids …: 

Breakup of fluids … … has been at the focus of scientific research for a long time Savart (1833) Rayleigh (1891) Water jets

Drop formation …: 

Drop formation … … is in general accompanied by satellite production (variation of drop sizes) Rutland & Jameson, J. Fluid Mech. 46, 267 (1971) Non-linear effects Linear theories (e.g. Rayleigh, 1879) Water jets

Jet breakup (linear theory): 

Jet breakup (linear theory) Observation (for water): mono-disperse & satellite-free production for X ≈ 0.69 only (i.e. certain choice of jet parameters: vjet, fnozzle, R0) Lord Rayleigh 1842 – 1919 Nobel Prize 1904

Sources of unwanted vibrations: 

Sources of unwanted vibrations Cooling devices (e.g. displacers in cold heads) Turbulent liquid flows Boiling (Tboil. – Tmelt. ≈ 5 K for H2, Ar, Xe, …)

Suppression of vibrations (1): 

Suppression of vibrations (1) Cooling with cryogenic liquids Ar N2 N2 He H2 droplets Ar droplets

Suppression of vibrations (2): 

Suppression of vibrations (2) Minimal temperature gradients Constant level of liquefied target gas Condenser Glass nozzle Heater for temperature fine-tuning Heater Heat exchanger ∆T < 5 K

Our pellet generators: 

Our pellet generators Jülich, FZJ PANDA prototype target Production of thin liquid jets and pellets from H2, D2, N2, Ar and other materials. Moscow, ITEP Thin liquid jets and pellets from N2, Ne, Ar, Kr and Xe. First observation of Ar and Xe jets and pellets. Moscow, MPEI Test of thermodynamic models for water drop production. Development of optical jet and pellet diagnostics.

PANDA prototype target: 

PANDA prototype target Operation principles: Vibration-free cooling 3 cooling stages: liquid N2 for pre-cooling evaporated He gas in heat exchanger evaporated He gas in condenser Advantages: No vibrations transferred to the nozzle Jet generation from various gases: H2, D2, O2, N2, Ne, Ar, Kr, Xe   Apparatus and method protected by: Russian Federation Patent (№ 2298890) German Patent (Anmeldung 10 2007 017 212.7)

Triple point chamber (TPC): 

Triple point chamber (TPC) He cooling lines condenser

Droplet & pellet diagnostics: 

Droplet & pellet diagnostics CCD cameras Analysis software Observation of jets and individual pellets Measurement of pellet size, shape, velocity and deflection angle from the sluice axis

Cryogenic droplets: 

Cryogenic droplets N2, ø = 17 µm H2, ø = 12 µm First observation of mono-disperse and satellite-free droplet production for cryogenic liquids !! Deviations from (“good old”) linear theory?

Jet parameters: 

Jet parameters

Deviations from linear theory !: 

Deviations from linear theory ! Cryogenic jets are significantly more resistant to decay than predicted Effect of surface evaporation …??? ? ? ! Lobserved Lobserved LRayleigh LRayleigh Submitted to PRL N2, ø = 17 µm H2, ø = 12 µm

New jet modes !: 

New jet modes ! Decrease of TPC pressure and/or jet velocity stronger evaporation strong effect on jets (bending) 2R0 = 17 µm Vjet = 1.0 m/s. TTPC = 74 K pTPC =300 mbar 2R0 = 12 µm Vjet = 0.8 m/s. TTPC = 14 K pTPC =130 mbar 2R0 = 150 µm Vjet = 4.0 / 3.9 / 3.0 m/s. TTPC = 300 K pTPC =3.0 / 0.8 / 0.9 mbar N2 H2 water Submitted to PRL

Properties of pellet flux: 

Properties of pellet flux Stable pellet production observed for H2, N2, Ar Frozen H2 and N2 pellets behind the sluice to the vacuum chamber Observation of pellet tracks with CCD cameras Radial pellet displacement (extrapolated to interaction point 1.2 meters below sluice) 1 mm –1 0 +1 –0.5 +0.5

Pellet flux: Conventional cooling: 

Pellet flux: Conventional cooling Measured at Uppsala target test station with line-scan camera (Ö. Nordhage) Cross section of pellet beam defined by skimmers Spread 3.73 mm

Ongoing tests (example): 

Ongoing tests (example) Scattering of laser light off H2 pellets … verification of narrow pellet beam Laser Photomultiplier Target vacuum chamber

Future tasks: 

Future tasks Complete automation system for target control Test of the fast part of the diagnostic system Stable production of pellets from O2, Ne, Kr, Xe Develop and test a pellet generator for frequencies ~100kHz Improve the droplet frequency stability after sluices Update of thermodynamic model using new experimental results Find sluice geometry for minimum angular distribution of pellets

Pellet generator @ PANDA: 

Pellet generator @ PANDA

Our team: 

Our team Further info: http://www.fz-juelich.de/ikp/pellet/index.shtml Forschungszentrum Jülich (FZJ) M.Büscher, P.Fedorets, D.Spölgen Institute for Theoretical and Experimental Physics (ITEP), Moscow A.Gerasimov, V.Balanutsa, V.Chernetsky, A.Dolgolenko, A.Demekhin, V.Goryachev, L.Gusev, S.Podchasky Moscow Power Engineering Institute (MPEI), Moscow A.Boukharov, I.Maryshev, A.Semenov “Sponsors”: BMBF (WTZ 96/634, 99/684), COSY-FFE, DFG (436 RUS 113/561, 436 RUS 113/733), EU/FP6, INTAS, ISTC 1966, RFBR