Design of MARCO, the New Solenoidal Detector Magnet for the ePIC Experiment at BNL

Journal Article · Wed Sep 10 00:00:00 EDT 2025 · IEEE Transactions on Applied Superconductivity

DOI:https://doi.org/10.1109/TASC.2025.3608471· OSTI ID:2997164

Calvelli, Valerio ^[1]; Berriaud, Christophe ^[1]; Genot, Clément ^[1]; Ghoshal, Probir K. ^[2]; Gopinath, Sandesh ^[2]; Juster, François-Paul ^[1]; Kleymenov, Victor ^[1]; Lottin, Jean-Pierre ^[1]; Quettier, Lionel ^[1]; Reymond, Hugo ^[1]; Segreti, Michel ^[3]; Sharma, Rahul ^[4]; Simon, Damien ^[1]; Stacchi, Francesco ^[1]; Sun, Eric ^[2]; Than, Roberto ^[4]; Wimmer, Roland ^[4]; Young, Daniel ^[2]; Aschenauer, Elke ^[4]; Ent, Rolf ^[2] ; Rajput-Ghoshal, R. ^[2]

---

1. Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA-Saclay), Gif-sur-Yvette (France). Institut de Recherche sur les Lois Fondamentales de l'Univers (IRFU); Univ. Paris-Saclay, Gif-sur-Yvette (France)
2. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
3. Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA-Saclay), Gif-sur-Yvette (France). Lois Fondamentales de l'Univers (IRFU); Univ. Paris-Saclay, Gif-sur-Yvette (France)
4. Brookhaven National Laboratory (BNL), Upton, NY (United States)

MARCO is the new superconducting solenoid for ePIC, the general-purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider at Brookhaven National Laboratory. Here, this 3.84 m long solenoid, with a bore diameter of 2.84 m, will provide a magnetic field of 2.0 T at the center with a nominal current of 4 kA at 4.5 K, for a total stored energy of 45 MJ. Its conductor is a NbTi Rutherford in Copper Channel (RICC), specially designed to stand the high mechanical loads induced by the magnetic field. Its copper stabilizer will assure the protection in case of quench. The coils are wound into six layers inside a thin external mandrel in brass, with a triple role of mechanical reinforcement, cryogenic support for the thermosiphon circuit and quench-back propagator. With a cold mass average radial thickness of just 7 cm, the magnet fulfills all the criterions of transparency for the particles directed to the hadronic calorimeter forecast around the cryostat. In this paper, the design of MARCO is presented, with a specific focus on the magnetic and quench analysis.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: AC05-06OR23177
• OSTI ID: 2997164
• Report Number(s): DOE/OR/23177--7832; JLAB-PHY--25-4272
• Journal Information: IEEE Transactions on Applied Superconductivity, Journal Name: IEEE Transactions on Applied Superconductivity Journal Issue: 8 Vol. 35; ISSN 1051-8223; ISSN 2378-7074; ISSN 1558-2515
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)
• Country of Publication: United States
• Language: English