A medical probe, comprising: an insertion tube having a distal end configured for insertion into a body of a patient and containing a lumen having an electrical conductor for conveying electrical energy; a conductive cap attached to the distal end of the insertion tube and coupled electrically to the electrical conductor, the cap comprising a side wall having multiple longitudinal bores therein; a plurality of thermocouples disposed in respective ones of the longitudinal bores, wherein the plurality of thermocouples comprises a first thermocouple positioned at a distal location in a given longitudinal bore and a second thermocouple positioned at a proximal location in the given longitudinal bore, wherein the first and second thermocouple in a given longitudinal bore are formed from a trifilar assembly comprising a first electrical conductor having a first composition and two respective second conductors having a second composition, wherein the first and second conductors are separated by and physically connected by insulating material to form the trifillar assembly, wherein the first and second thermocouple are formed by respective solder beads connecting respective exposed portions of the second conductors to respective exposed portions of the first conductor; and an electrically and thermally conductive cement filling the longitudinal bores so as to embed the thermocouples in the electrically and thermally conductive cement and secure the thermocouples in the bores while making electrically conductive contact between the thermocouples and the conductive cap. an insertion tube having a distal end configured for insertion into a body of a patient and containing a lumen having an electrical conductor for conveying electrical energy; a conductive cap attached to the distal end of the insertion tube and coupled electrically to the electrical conductor, the cap comprising a side wall having multiple longitudinal bores therein; a plurality of thermocouples disposed in respective ones of the longitudinal bores, wherein the plurality of thermocouples comprises a first thermocouple positioned at a distal location in a given longitudinal bore and a second thermocouple positioned at a proximal location in the given longitudinal bore, wherein the first and second thermocouple in a given longitudinal bore are formed from a trifilar assembly comprising a first electrical conductor having a first composition and two respective second conductors having a second composition, wherein the first and second conductors are separated by and physically connected by insulating material to form the trifillar assembly, wherein the first and second thermocouple are formed by respective solder beads connecting respective exposed portions of the second conductors to respective exposed portions of the first conductor; and wherein the plurality of thermocouples comprises a first thermocouple positioned at a distal location in a given longitudinal bore and a second thermocouple positioned at a proximal location in the given longitudinal bore, wherein the first and second thermocouple in a given longitudinal bore are formed from a trifilar assembly comprising a first electrical conductor having a first composition and two respective second conductors having a second composition, wherein the first and second conductors are separated by and physically connected by insulating material to form the trifillar assembly, wherein the first and second thermocouple are formed by respective solder beads connecting respective exposed portions of the second conductors to respective exposed portions of the first conductor; and an electrically and thermally conductive cement filling the longitudinal bores so as to embed the thermocouples in the electrically and thermally conductive cement and secure the thermocouples in the bores while making electrically conductive contact between the thermocouples and the conductive cap.