The ornamental design for a detector, as shown and described.
FIG. 1 is a perspective view of a detector showing my new design;
FIG. 2 is right side elevational view showing the design for the detector of FIG. 1;
FIG. 3 is a left side elevational view showing the design for the detector of FIG. 1;
FIG. 4 is a rear elevational view showing the design for the detector of FIG. 1;
FIG. 5 is a front elevational view showing the design for the detector of FIG. 1;
FIG. 6 is a top elevational view showing the design for the detector of FIG. 1; and,
FIG. 7 is a bottom elevational view showing the design for the detector of FIG. 1.
The broken line showing of the bottom of the design inside of the peripheral boundary is included for the purpose of illustrating portions of the “article” and forms no part of the claimed design.