APPLICATIONS OF MAGNESIUM DIBORIDE TO PARTICLE PHYSICS Riccardo Musenich Istituto Nazionale di Fisica Nucleare Genova

Summary Historical introduction Applications of superconductors Superconductors in particle physics Applications of new materials MgB 2 : overview italian programs INFN activity future INFN programs (if any)

H.Kamerlingh Onnes, Commun. Phys. Lab. Univ. Leiden, 122 e 124, : discovery of superconductivity

Starting from the fourties many superconducting materials, like niobium nitride and niobium-tin *, have been discovered, but only in 1962 the first “industrial scale” superconducting wires (based on niobium-titanium) have been developed by Westighouse. In 1986 HTCS (La 1.85 Ba 0.15 CuO 4, T c =30K) have been discovered **. The higher critical temperature for HTCS is 138 K (Hg 0.8 Tl 0.2 Ba 2 Ca 2 Cu 3 O 8.33 ) *** *B. T. Matthias et al., Phys. Rev. 95, 1435 (1954) ** J.G.Bednorz, K.A.Müller, Z.Phys. B, Cond. Matter, 64, (1986) ***P. Dai et al., Physica C, 243, (1995)

Applications of superconductivity Energy production and transport Alternators Transformers Cables Energy storage (SMES) Current limiters (FCL) Trasports magnetic levitation motors MHD propulsion

Electronics and communications filters antennas microprocessors Industrial applications Magnets for: magnetic separation crystal growth chemical processes Sensors SQUID Applications of superconductivity

Medicine MRI biomagnetic measurements Applications of superconductivity Research laboratory magnets NMR spectrometers magnets for nuclear fusion accelerator components (magnets and rf cavities) superconducting detectors SQUID

M€% R&D41518 (30) MRI1900 (900)80 (66) other applications552 (4) TOTAL2370 (1370)100 CONECTUS, december 2001 WORLDWIDE SUPERCONDUCTIVITY MARKET YEAR 2000

Applications of HTCS (YBCO e BSCCO) At present, technical difficulties in handling the materials and high costs (200 €/kA  m) limit, the HTCS to niche applications. The technological research looks toward the energy transport and to devices like FCL and transformers. HTCS (YBCO e BSCCO) market: 15 M€  1%

Among the research application, particle physics largely uses superconducting materials, mainly for magnets and accelerating cavities. The choice between resistive and superconductive devices is generally related to technical aspects: the superconductor technology is often the only possibility to achieve the required performances.

superconductivity in nuclear and subnuclear physics accelerating cavities RecyclotronSTANFORD MUSLUniversity of Illinois S-DalinacDarmstat TRISTANKEK HERADESY CEBAFJEFFERSON LAB LEP CERN TESLA TFDESY J.Proch, Rep. Prog. Phys., 61, , 1998

Argonne National Laboratory Stony Brook Florida State University University of Washington CEN – Saclay JAERI INFN – LNL ANU – Canberra J.Proch, Rep. Prog. Phys., 61, , 1998 superconductivity in nuclear and subnuclear physics accelerating cavities

TEVATRONFNAL RHICBNL HERADESY LHC (under construction) CERN superconductivity in nuclear and subnuclear physics magnets for accelerators

ChalK River S.C.Canada K500MSU K800INFN – LNS K1200MSU AGORKVI Groningen + other 3 S.C. under construction superconductivity in nuclear and subnuclear physics magnets for accelerators

CELLO DELPHI CDF ZEUS TOPAZ BABAR VENUS ATLAS ALEPH CMS The first large superconducting detector magnet was constructed in the sixties: it was the solenoid for the 12 ft bubble chamber of Zero Gradient Synchrotron (Argonne National Laboratory) superconductivity in nuclear and subnuclear physics detector magnets

widest used superconducting materials : Nb-Ti (magnet conductors) Nb 3 Sn(magnet conductors) Nb(accelerating cavities) At present, the material under development are: alloyed Nb 3 Sn, Nb 3 Al, YBCO, BSCCO and MgB 2

R S =R BCS +R RES Pb Nb other material (NbN, Nb 3 Sn …) Niobium nitride superconductivity in nuclear and subnuclear physics materials for accelerating cavities

To reduce the thermal load at low temperature, the LHC magnets will be equipped with HTCS current leads. This one is the first large scale application of the HTCS in high energy physics. HTCS superconductivity in nuclear and subnuclear physics

MgB 2 T c = 39 K  ITCS J.Nagamatsu, N.Nakagawa, T.Muranaka, Y.Zenitani, J.Akimitsu Nature (2001) MgB 2 is the binary compound with the highest critical temperature

The material characteristics seems favourable for technological applications: high critical temperature (39 K) B c2  15 T no weak links (  =5 nm) low anisotropy high critical current density (J c  5  10 9 A/m 2 a 20 K e 0 T) low cost (extimated: 5 €/kA  m) On the other hand, the irreversibility field is relatively low: 4 Tesla at 20 K

Thanks to the know-how and the technologies developed for the production of HTCS conductors, few month after the discovery of the superconducting properties of MgB 2, wires and tapes became available in several meter lengths.

production technique of magnesium diboride conductors: in situ Powder in tubes (PIT) ex situ

Like Nb 3 Sn, MgB 2 requires a high temperature heat treatment to achieve good transport properties*. Two routes can be followed to construct a magnet: REACT & WIND WIND & REACT * Ex-situ PIT conductors have high critical current even without heat treatment!

Thin films can be deposited by : Sputtering Evaporation Laser ablation from MgB 2 cathode from precursor cathodes reactive sputtering

Thin MgB 2 films Resonant cavities Squid Detectors

MgB 2 Research programs on MgB 2 in Italy

Research (mainly fundamental) with ordinary funds (CNR, INFM, Universities) Industrial R&D (Ansaldo Superconduttori, Columbus Superconductors, Edison, Europa Metalli, Pirelli) INFN (Ma-Bo project) INFM (MIUR funded project)

Ma-Bo the INFN program ( ) on magnesium diboride applications to nuclear and particle physics Genova Frascati National Laboratories Legnaro National Laboratories Milano Napoli Torino 30 people involved (about 10 FTE).

Ma-Bo The research project Ma-Bo aims to understand if magnesium diboride could be used for particle physics applications. The research activities are related to: Magnets Thin films for cavities Thin films for detectors and other devices

Ma-Bo is in collabotation with: ENEA INFM Universities Ansaldo Superconduttori Columbus Superconductors

I = 1 A V = 400  460 V t = 10 min Mg MgB 2 Nb box Platform Heater Plasma Cathodes Mg pellets Substrate Ar atmosphere T “cold” B R.Vaglio, INFN and University of Naples Thin films

Problems in using MgB 2 for rf resonant cavities: – MgB 2 is a double gap superconductor – A homogeneous, pure (single phase) film must be deposited onto large area substrates – The material is chemically instable (exposed to the atmosphere)

e -  /KT R s res  1 m  R.Vaglio, INFN and University of Naples f = 20 GHz

XPS spectrum of a MgB 2 film

XPS spectrum of a MgB 2 film (B 1s)

XPS spectrum of a MgB 2 film (Mg 2s)

B(mT) magneto-optical analysis on MgB 2 films Dendritic flux penetration E.Mezzetti, INFN and Politecnico di Torino

100 meters Production of MgB 2 tape (PIT method) at LAMIA laboratory (INFM) 3.5 mm x 0.3 mm SC fill factor 15-20%

n G.Grasso, INFM–LAMIA Genova

MgB 2 “React&Wind” solenoid wound by Ansaldo Superconduttori with 80 m long INFM/Columbus tape Ø 145 mm

B = 1.35 mT/A, (coil center) B = 2.15 mT/A (B MAX at the conductor) React & wind technique 6 layers 27 turns/layer Diameter = 15 cm

Solenoid test in liquid helium bath Superconducting for most of the length No resistance observed at the layer joggle Localized dissipation at the inner electrical exit Despite the localizad dissipation (4 W at 47 A) the solenoid was able to carry 53 A before quenching (11 mT at the conductor, 6 mT at coil center)

Pancake coil wound by Ansaldo Superconduttori with 40 m tape (INFM/Columbus Superconductors) 20 cm

Test of the pancake coils in liquid helium bath Both the coils were fully superconducting Pancake #1 reached 215 A (B MAX =0.47 T, B C = 0.13 T) Pancake #2 reached 335 A (B MAX =0.74 T, B C = 0.20 T)

Several problems must be solved but the feasibility of MgB 2 magnets is clearly demonstrated

Perspective for ITCS (MgB 2 ) in nuclear and subnuclear physics Easy to produce. Low cost of the material. No weak link. High critical current density. applications: cryogen free, low field, superconducting magnets

Powder density Grain dimension Nanoparticles inclusions Lattice disorder Doping Texturing J c H c2, H irr Improvement of MgB 2 properties

CONCLUSIONS At present, superconducting devices like cavities and magnets, based on niobium and niobium-titanium respectively, are largely used in particle physics. Till now, neither MgB 2 nor other superconducting materials can compete with niobium for application in accelerating cavities. Among the new superconductors, magnesium diboride seems a good candidate for the construction of magnets. Low field magnets will be probably the first step but there are several indication about the possibility of a field improvement.